v5: Forms update (#28450)

* Initial spike of consolidated form checks

* Stub out forms rearrangement

- Prepping to drop non-custom file and range inputs
- Prepping to merge custom and native checks and radios (with switches)
- Prepping to merge custom select with form select
- Moving docs arround so forms has it's own area given volume of CSS

* Move input group Sass file to forms subdir

* Start to split and move the docs around

* Simpler imports

* Copyediting

* delete overview file

* Remove commented out code

* remove the custom-forms import

* rewrite flex-check as form-check, replace all custom properties

* Remove old forms doc

* stub out new subpage link section

* update migration guide

* Update nav, forms overview in page nav, and descriptions

* fix check bg position

* fix margin-top calculation

* rename .custom-select to .form-select

* Update validation styles for new checks

* add some vertical margin, fix inline checks

* fix docs examples

* better way to do this contents stuff, redo the toc while i'm at it

* page restyle for docs while here

* un-callout that, edit text

* redo padding on toc

* fix toc

* start to cleanup checks docs

* Rewrite Markdown tables into HTML

* Redesign tables, redo their docs

* Replace Open Iconic icons with custom Bootstrap icons

* Redesign the docs navbar, add a subheader, redo the sidebar

* Redesign docs homepage a bit

* Simplify table style overrides for docs tables

* Simplify docs typography for page titles and reading line length

* Stub out icons page

* Part of sidebar update, remove migration from nav.yml

* Move toc CSS to separate partial

* Change appearance of overview page

* fix sidebar arrow direction

* Add footer to docs layout

* Update descriptions

* Drop the .form-group class for margin utilities

* Remove lingering form-group-margin-bottom var

* improve footer spacing

* add headings to range page

* uncomment form range css

* Rename .custom-range to .form-range

* Drop unused docs var

* Uncomment the comment

* Remove unused variable

* Fix radio image sizing

* Reboot update: reset horizontal ul and ol padding

* de-dupe IDs

* tweak toc styles

* nvm, fix dropdown versions stuff

* remove sidebar nav toggle for now

* broken html

* fix more broken html, move css

* scss linting

* comment out broken helper docs

* scope styles

* scope styles

* Fixes #25540 and fixes #26407 for v5 only

* Update sidebar once more

* Match new sidenav order

* fix syntax error

* Rename custom-file to form-file, update paths, update migration docs for previous changes in #28696

* rename back

* fix size and alignment

* rename that back too

site/content/docs/4.3/components/dropdowns.md

@@ -811,7 +811,7 @@ Regardless of whether you call your dropdown via JavaScript or instead use the d
 
 Options can be passed via data attributes or JavaScript. For data attributes, append the option name to `data-`, as in `data-offset=""`.
 
-<table class="table table-bordered table-striped">
+<table class="table">
   <thead>
     <tr>
       <th style="width: 100px;">Name</th>
@@ -862,26 +862,100 @@ Note when `boundary` is set to any value other than `'scrollParent'`, the style
 
 ### Methods
 
-| Method | Description |
-| --- | --- |
-| `toggle` | Toggles the dropdown menu of a given navbar or tabbed navigation. |
-| `show` | Shows the dropdown menu of a given navbar or tabbed navigation. |
-| `hide` | Hides the dropdown menu of a given navbar or tabbed navigation. |
-| `update` | Updates the position of an element's dropdown. |
-| `dispose` | Destroys an element's dropdown. |
-| `_getInstance` | *Static* method which allows you to get the dropdown instance associated with a DOM element |
+<table>
+  <thead>
+    <tr>
+      <th>Method</th>
+      <th>Description</th>
+    </tr>
+  </thead>
+  <tbody>
+    <tr>
+      <td><code>toggle</code></td>
+      <td>
+        Toggles the dropdown menu of a given navbar or tabbed navigation.
+      </td>
+    </tr>
+    <tr>
+      <td><code>show</code></td>
+      <td>
+        Shows the dropdown menu of a given navbar or tabbed navigation.
+      </td>
+    </tr>
+    <tr>
+      <td><code>hide</code></td>
+      <td>
+        Hides the dropdown menu of a given navbar or tabbed navigation.
+      </td>
+    </tr>
+    <tr>
+      <td><code>update</code></td>
+      <td>
+        Updates the position of an element's dropdown.
+      </td>
+    </tr>
+    <tr>
+      <td><code>dispose</code></td>
+      <td>
+        Destroys an element's dropdown.
+      </td>
+    </tr>
+    <tr>
+      <td><code>_getInstance</code></td>
+      <td>
+        Static method which allows you to get the dropdown instance associated with a DOM element.
+      </td>
+    </tr>
+  </tbody>
+</table>
 
 ### Events
 
 All dropdown events are fired at the `.dropdown-menu`'s parent element and have a `relatedTarget` property, whose value is the toggling anchor element.
-`hide.bs.dropdown` and `hidden.bs.dropdown` events have a `clickEvent` property (only when the original event type is `click`) that contains an Event Object for the click event.
+`hide.bs.dropdown` and `hidden.bs.dropdown` events have a `clickEvent` property (only when the original Event type is `click`) that contains an Event Object for the click event.
 
-| Event | Description |
-| --- | --- |
-| `show.bs.dropdown` | This event fires immediately when the show instance method is called. |
-| `shown.bs.dropdown` | This event is fired when the dropdown has been made visible to the user (will wait for CSS transitions, to complete). |
-| `hide.bs.dropdown` | This event is fired immediately when the hide instance method has been called. |
-| `hidden.bs.dropdown`| This event is fired when the dropdown has finished being hidden from the user (will wait for CSS transitions, to complete). |
+<table>
+  <thead>
+    <tr>
+      <th>Method</th>
+      <th>Description</th>
+    </tr>
+  </thead>
+  <tbody>
+    <tr>
+      <td>
+        <code>show.bs.dropdown</code>
+      </td>
+      <td>
+        Fires immediately when the show instance method is called.
+      </td>
+    </tr>
+    <tr>
+      <td>
+        <code>shown.bs.dropdown</code>
+      </td>
+      <td>
+        Fired when the dropdown has been made visible to the user and CSS transitions have completed.
+      </td>
+    </tr>
+    <tr>
+      <td>
+        <code>hide.bs.dropdown</code>
+      </td>
+      <td>
+        Fires immediately when the hide instance method has been called.
+      </td>
+    </tr>
+    <tr>
+      <td>
+        <code>hidden.bs.dropdown</code>
+      </td>
+      <td>
+        Fired when the dropdown has finished being hidden from the user and CSS transitions have completed.
+      </td>
+    </tr>
+  </tbody>
+</table>
 
 {{< highlight js >}}
 var myDropdown = document.getElementById('myDropdown')