* Tear down the Authentication monolith
Major changes:
* Turn the usage functions into a proper service `AuthenticationUsageService`
* Pull out the access data stuff into its own service `AuthenticationAccessService`
* Pull out things that make sense as actions `ManageTrustedExtensionsForAccount` `SignOutOfAccount`
* Pull out random registry stuff into a proper authentication contribution
* Pull out everything else that is extension specific into its own class (and eventually it should be in MainThreadAuthentication)
* Have the new `AuthenticationService` return a provider instead of having specific methods for getting the `label` or `supportsMultipleAccounts`
* fix tests
* fix tests
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