Update to `@rollup/plugin-babel`

Allows use of background-color and more. Fixes #29033 for v5.

For some reason, custom checks in CSS columns need a new stacking order to maintain visibility. This PR adds `z-index: 1` to trigger that new stacking order. Since v5's forms are being redone entirely, and we're dropping IE10/11 there, I think this is totally fine to ship with v4 only. Will need to check v5's forms it in Edge though.

Fixes #29607

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Co-authored-by: XhmikosR <xhmikosr@gmail.com>

Co-authored-by: XhmikosR <xhmikosr@gmail.com>

Turns out this applies to IE11 as well as IE10, so this clarifies the docs callout.

Closes #25242

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Co-authored-by: XhmikosR <xhmikosr@gmail.com>

- Closes #30796

They are not included in npm.

We missed it in #30562

Add a test about the scrollbar issue on non-integer width

Refs #30772

Remove moot fail-fast option

* remove favicons meta tags
* copy the two brand images we use in the examples
* copy dist and brand images into an assets folder

While it might not be possible to invalidate the cache by changing test.yml, this should speed things up a lot due to `bundle i` taking most of the time.

This partially reverts commit 6c464938.

Make the `docs-compile` one an alias of `docs-build`.

- 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