Extension:CentralNotice/Notes/Extension registration

Notes for finalizing the conversion of CentralNotice to use extension registration. Current work is here: Gerrit change 186899.

Copied code to verify

• Autoloaded classes (extension.json)  Done (PS 33)
• API modules and list modules (extension.json)  Done (PS 33)
• Hooks (extension.json and CentralNoticeHooks::onRegistration())  Done (PS 35)
• Special pages (extension.json)  Done (PS 33)
• RL modules (extension.json)  Done (PS 33)
• Config variables and defaults (extension.json)  Done (PS 33)

Functionality to smoke test

• UserMerge integration  Done (as merged to master branch)
• TranslationExtension integration Test on beta cluster
• User rights  Done (PS 36)
• Namespace registration  Done (as merged to master branch)
• RL loading (modules loaded on most pages vs. those on Special and edit pages)  Done (PS 36)
• Variables sent to JS  Done (PS 36)
• Presence of SiteNotice div  Done (PS 36)
• PHP and JS unit tests  Done (PS 36)
• EventLogging schema Test on beta cluster
• API  Done (PS 36)