KeyChain - Credential management app follow ups

* Add KeyChainService API isCredentialManagementApp
* Access control to allow the credential management
  app to call KeyChainService API
  getCredentialManagementAppPolicy.

Bug: 177979648
Test: atest android.devicepolicy.cts.CredentialManagementAppTest
Change-Id: I7ad446b6966ee4e76b03e28990fa8e395653511d
1 file changed