[PP1] Refactor breadcrumb

Working on this now!

Confirmed in slack, the breadcrumb's "back to site" link is missing the back arrow on the left and the pipe on the right (see screenshot). Currently unsure what "Fix issues with current typing" was about so I'll leave that piece of feedback for now.

Ready for review!

To test, visit a create node page (eg. https://mr121-92dvfb1kuzo3pucqszjvehwaiwtuwlfm.tugboatqa.com/en/node/add...). Ensure the breadcrumb's "back to site" arrow and pipe are showing.

@ckrina, if you remember what proposed resolution #2 was about, let me know and I can push a fix for that as well.

Thank you for you work here!

Few notes:

1. When I remove Claro breadcrumbs.css i got breadcrumbs broken.
https://gyazo.com/3913fcf7cb6b644992cdc2fc78e6d4f0
I think it should be independent from any theme.

2. Instead of using `icons::before` in absolute position imo better to use `display:flex` with `gap` for parent element.

3. We still use some variables from other places `var(--color-text); var(--color-link-hover)`.
Should be scoped with module variables.

4. Please run `yarn lint:css --fix` before commit.

Also couple of moments in MR overview. Please take a look.

Added small code example how we can use :where

https://jsfiddle.net/finnsky/uhmgrj68/7/

We libraryRemove claro breadcrumbs styles in module. And in same time will not affect styles of other themes.

because lower specifity.
:where(.breadcrumbs .breadcrumbs__link) < breadcrumbs__link

We may try like this.

The problem here is that we can't disable all breadcrumbs from all themes. Breadcrumbs can be visible even on user pages. We can try to have simple CSS only for admin toolbar (exclusively) by making classnames unique, so instead of having where(.breadcrumbs .breadcrumbs__link) < breadcrumbs__link we could have only .admin-breadcrumbs {}. Smth like this

We agreed with @finnsky to postpone the work here until we sort out 📌 Create a functional prototype of the new top contextual bar Needs work because the work happening there might solve this.