Fix link colors for admin schemes that personalize it using the $link SASS variable

[youknowriad]

Custom link colors used on admin schemes are broken in some instances. They are using the default link color.

• For button links
• And a specific case in the customizer

[youknowriad]

The close link was broken.

https://core.trac.wordpress.org/ticket/50536

This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See [GitHub Pull Requests for Code Review](​https://make.wordpress.org/core/handbook/contribute/git/github-pull-requests-for-code-review/) in the Core Handbook for more details.

[youknowriad]

In 48332:

Administration: Fix link colors for admin schemes that personalize it using the $link SASS variable.

The new "moderne" admin scheme color personalizes the link color using the $link SASS variable.
The link color doesn't apply consistently in the admin to all links, especiall button links.

Fixes #50536.

[afercia]

[48332] introduced a regression: some "destructive action" buttons aren't red any longer, in all the color schemes.

This happens because now button-link from the color schemes overrides button-link-delete.

Red destructive action controls are a well established convention in core, as any potentially action that deletes content should be visually well distinguished.

See attached screenshot for the destructive action in the Widgets. Happens also in the customizer.

Worth also reminding that when changing variables in the _admin.scss file, the change will likely impact plugins that extend the color schemes. At the very least, this change should have a dev-note.

Reopening as the red color for destructive action should be restored.

[afercia]

Destructive action in WordPress 5.4: red (Ectoplasm color scheme)

[afercia]

Destructive action in WordPress trunk: blue (Ectoplasm color scheme)

[youknowriad]

Good catch @afercia I'll take a look shortly.

[youknowriad]

Fix remove link colors for admin schemes

[youknowriad]

@afercia the last patch should solve the issue. Would you mind checking?

[afercia]

@youknowriad I'm afraid I'm a bit busy, Beta 1 day :)

Given this is a new feature introduced in this release cycle, I think it can be addressed also during Beta.

[youknowriad]

Thanks for the notice, I'll find someone to confirm the fix and see if I can commit it before beta 1

[youknowriad]

In 48376:

Administration: Fix remove links color.

Fix regression introduced in [48332] where the specificity
of the admin scheme link colors was higher than the remove link colors.

Props afercia.
Fixes #50536.