Enable several of the ULS modules so they can be used in a mobile context,
in particular by the Translate Extension
Changes:
* Create a ext.uls.common module that can be loaded safely on mobile
* Only add the ext.uls.init entry point module on desktop (ensured by
the use of targets). On mobile it has no impact other than to increase
the amount of bytes shipped to users.
* Note various modules have not been enabled for mobile usage.
Bug: T102922
Change-Id: If2808886f0bfa153f5918e3c7536e88641028da9
9e0dcbde35