Implement startRemoteLockscreenValidation.

Define parcelables for new APIs - go/setup-lskf-apis
They are needed to test implementation and will be  added to SystemApi in a separate change - ag/21091787
Move feature flag check to RecoverableKeyStoreManager initialization.

Bug: 254335492
Test: atest com.android.server.locksettings.recoverablekeystore
Change-Id: Idfeb9583fcc29676a18116a5ef27dba9012aac09

Change-Id: Ie436b302ab670b4e6e77b8d2a581fd61a47529fc