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/modal.md

@@ -590,7 +590,7 @@ Embedding YouTube videos in modals requires additional JavaScript not in Bootstr
 
 Modals have three optional sizes, available via modifier classes to be placed on a `.modal-dialog`. These sizes kick in at certain breakpoints to avoid horizontal scrollbars on narrower viewports.
 
-<table class="table table-bordered table-striped">
+<table class="table">
   <thead>
     <tr>
       <th>Size</th>
@@ -737,7 +737,7 @@ Create a modal with a single line of JavaScript:
 
 Options can be passed via data attributes or JavaScript. For data attributes, append the option name to `data-`, as in `data-backdrop=""`.
 
-<table class="table table-bordered table-striped">
+<table class="table">
   <thead>
     <tr>
       <th style="width: 100px;">Name</th>
@@ -833,10 +833,10 @@ var modal = bootstrap.Modal._getInstance(myModalEl) // Returns a Bootstrap modal
 
 Bootstrap's modal class exposes a few events for hooking into modal functionality. All modal events are fired at the modal itself (i.e. at the `<div class="modal">`).
 
-<table class="table table-bordered table-striped">
+<table class="table">
   <thead>
     <tr>
-      <th style="width: 150px;">Event Type</th>
+      <th style="width: 150px;">Event type</th>
       <th>Description</th>
     </tr>
   </thead>