Add credential management app access control DPM

Background
* This is part of the work to support
  a credential management app on
  unmanaged devices.

Changes
* Add isCredentialManagementApp access
  control check to the following DPM API
  methods:
   - installKeyPair
   - removeKeyPair
   - generateKeyPair
   - setKeyPairCertificate

Bug: 165641221
Test: Manual testing with TestDPC
Change-Id: Ib88f077ee1f26c08e648ab8b4bb3544b42078d57