Add escrow token support to synthetic password flow

Escrow token provides an alternative way to derive synthetic password for a
given user. In the new flow, a pre-provisioned escrow token
should be able to do anything the user password can do, since they both
derives the synthetici password which is the master key in the new auth flow.

Test: runtest frameworks-services -c com.android.server.SyntheticPasswordTests
Bug: 33126414
Change-Id: Ib5ee38fd61f66de3245427ce992ebc12f1873a26