Add new interaction utilities and role attr to Reboot (#30562)

- Adds .user-select-* utils from v5
- Adds button role attribute util, one of the top requested features in our issues for adding pointer cursors
- Adds new docs page to demonstrate both
- Includes Sass list for customizing user select

site/_data/nav.yml

@@ -64,6 +64,7 @@
     - title: Flex
     - title: Float
     - title: Image replacement
+    - title: Interactions
     - title: Overflow
     - title: Position
     - title: Screen readers