R1:97c16997561b

Fix transaction title rendering for AuthenticationConfigs

Summary: I was poking around in `PhabricatorAuthProviderViewController` and noticed that none of the subclass-specific rendering was working. Figured out that no one ever calls `PhabricatorAuthProviderConfigTransaction->setProvider()`, so instead of adding all those calls, just pull the provider out of the config object.

Test Plan:
Before: {F6598145}
After: {F6598147}

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin…