* Add license header where missing.
* Add missing `@since` (1.17 for most classes), except
ResourceLoaderLessVarFileModule since 1.32 (1bc62c548c).
* Remove duplicate file-level description for class-only files,
merge with the class description instead.
* Remove my own `@author` annotation from one file.
* Mark core's own FileModule subclasses as `@internal`, except
for the following which we support use of in extensions:
ResourceLoaderLessVarFileModule,
ResourceLoaderOOUIIconPackModule, and
ResourceLoaderWikiModule.
Change-Id: I336af2e4ccdbe2512594e8861b72628d24194e41
mw.ForeignApi is an extension of mw.Api, automatically handling
everything required to communicate with another MediaWiki wiki via
cross-origin requests (CORS).
Authentication-related MediaWiki extensions may extend it further to
ensure that the user authenticated on the current wiki will be
automatically authenticated on the foreign one. A CentralAuth
implementation is provided in I0fd05ef8b9c9db0fdb59c6cb248f364259f80456.
Bug: T66636
Change-Id: Ic20b9682d28633baa87d22e6e9fb71ce507da58d
