Add an OS-FEDERATION section to scoped federation tokens

In this change, we add an OS-FEDERATION section to the user
section in a scoped federation token. We currently do the same
for unscoped tokens. This will also help with revocation events,
specifically revoking tokens based on IDP id.

Change-Id: Ibcb12a4a9db45351127458a96de1161de55d5a18
Closes-Bug: #1351038
Merge "Add an OS-FEDERATION section to scoped federation tokens"