fix: move packages/ui into the main source

[smalluban]

Moves all of the modules of packages/ui into the main source:

• Module global into the src/ui, other modules into the specific pages, where they were used
• Unifies the panel/onboarding styling into a single ui/styles.css loaded automatically with the ui module
• Unifies component naming prefixes - global component with ui-, page components with page name prefix, like onboarding- or settings-
• Minor fixes to the global components - missing hover states, cleared font sizing, etc

I did all of the smoke tests on Firefox and Chrome. However, the PR contains mainly visual changes, so please check out the package too when reviewing.

[chrmod]

I've scan the changes and all looks good. The PR could have been smaller if you would decide tho keep the previous naming scheme with gh- prefix.
We have to test the changes manually to be sure all if fine.

[github-actions]

Builds for commit 4488d10:

• ghostery-chromium-10.4.7-4488d10
• ghostery-firefox-10.4.7-4488d10