[components] Merge https://github.com/mozilla-mobile/android-components/pull/7473...

[components] Merge https://github.com/mozilla-mobile/android-components/pull/7473 https://github.com/mozilla-mobile/android-components/pull/7478 https://github.com/mozilla-mobile/android-components/pull/7485 (part 1)

7473: Bug 1647821 - Make `onExperimentUpdated` execute when using debug tools. r=pocmo a=travis79

7478: Import strings from android-l10n. r=pocmo a=mozilla-l10n-automation-bot

n/t

7485: Issue https://github.com/mozilla-mobile/android-components/issues/7484 - Import v12.0.0 of webcompat system addon. r=pocmo a=denschub

Imports the current release of the WebCompat System Addon with the sources already landed in `mozilla-central`. Fixes https://github.com/mozilla-mobile/android-components/issues/7484.

Co-authored-by: Travis Long <tlong@mozilla.com>
Co-authored-by: Mozilla L10n Automation Bot <release+l10n-automation-bot@mozilla.com>
Co-authored-by: Dennis Schubert <dschubert@mozilla.com>