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

scss/_reboot.scss

@@ -333,6 +333,13 @@ select {
   text-transform: none; // Remove the inheritance of text transform in Firefox
 }
 
+// Set the cursor for non-`<button>` buttons
+//
+// Details at https://github.com/twbs/bootstrap/pull/30562
+[role="button"] {
+  cursor: pointer;
+}
+
 // Remove the inheritance of word-wrap in Safari.
 //
 // Details at https://github.com/twbs/bootstrap/issues/24990