R1:5721560663de

Use modern UI for OAuthServer details page

Summary: Mostly just UI updates and policy enforcement. Improves error message when trying to authorize an already-authorized application.

Test Plan:
{F131584}

{F131585}

{F131586}

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D8564