Improve styling consistency of links within notices

[afercia]

Notices (in a general sense, including errors, "nags", warnings, etc.) displayed in the admin can have links in their messages. Sometimes these links are barely noticeable, for example when they're inside a sentence and color alone is not sufficient to distinguish them from the surrounding text:

Sometimes they're a little better because the context helps understand they're links, even if they're not underlined:

Sometimes they're underlined:

More examples:

Sometimes they have a trailing dot:

Sometimes not:

And some edge cases where the context helps but the consistency could be improved:

For accessibility, links inside lines or blocks of text should be always underlined. Looks like making them always underlined would be a pretty simple and effective improvement I'd strongly recommend :) Any thoughts more than welcome.

[rianrietveld]

+1 for links in this examples underlined

[afercia]

The two last screenshots above are somewhat special cases, maybe they would need some design feedback.

[afercia]

In 35801:

Notices: improve styling consistency of links within notices.

For accessibility, links inside lines or blocks of text should be always underlined.

Props walbo.
Fixes #34606.