Refactor OpenID provider pattern matching for reuse

We want to add auth.allowedOpenID, to filter which providers can be
used by an end-user on a particular server installation.  Moving the
matching code out of AuthConfig allows us to export this into the UI
where we can filter things earlier.

Change-Id: I917d1a3d2fc2654dead812879b2d3c1a3e89bb95
Signed-off-by: Shawn O. Pearce <sop@google.com>
2 files changed