Chat follow-up design fixes

[clauxx]

Bug Report

Address the follow-up chat design review issues and the additional comment from #18059.

Parent issue for:

1. Fix chat messages spacings #19013
2. Fix chat action buttons pressed color #19021
3. Fix message from long-press bottom sheet #19053
4. Fix chat's mute sheet and toast #19058
5. Fix the background of navbar buttons in chat header #19095

[churik]

I believe can be closed, reopen if still relevant