[UI] Sass Deprecation Warnings

[zofskeez]

Description

When building Vault UI, Sass was outputting a number of deprecation warnings, both from within the codebase as well as from dependencies. This PR fixes the deprecation warnings and silences warnings from dependencies to clean up the build output and update to current sass patterns.

Note that sass-migrator made the majority of the changes. After the migrator run there were a handful of errors where a stylesheet was extending a class like so:

.toolbar-link {
  @extend .button;
}

This no longer works because of extension scope since the selector .button is not in the stylesheet. For these errors, @use was added:

@use '../core/buttons.scss';

.toolbar-link {
  @extend .button;
}

No more deprecation warnings from sass 🎉

I didn't notice any styling that was impacted by the updates but it would be good to test by clicking around and keeping an eye out for things that look off.

Screen.Recording.2025-03-12.at.2.06.05.PM.mov

TODO only if you're a HashiCorp employee

• Backport Labels: If this fix needs to be backported, use the appropriate backport/ label that matches the desired release branch. Note that in the CE repo, the latest release branch will look like backport/x.x.x, but older release branches will be backport/ent/x.x.x+ent.
  • LTS: If this fixes a critical security vulnerability or severity 1 bug, it will also need to be backported to the current LTS versions of Vault. To ensure this, use all available enterprise labels.
• ENT Breakage: If this PR either 1) removes a public function OR 2) changes the signature
  of a public function, even if that change is in a CE file, double check that
  applying the patch for this PR to the ENT repo and running tests doesn't
  break any tests. Sometimes ENT only tests rely on public functions in CE
  files.
• Jira: If this change has an associated Jira, it's referenced either
  in the PR description, commit message, or branch name.
• RFC: If this change has an associated RFC, please link it in the description.
• ENT PR: If this change has an associated ENT PR, please link it in the
  description. Also, make sure the changelog is in this PR, not in your ENT PR.

[github-actions]

Build Results:
All builds succeeded! ✅

[github-actions]

CI Results:
All Go tests succeeded! ✅

[emoncuso]

I love it!

[emoncuso]

Not within scope of this PR, but we should probably convert these over to HDS tokens.