Add caller check to com.android.credentials.RESET

* Only the Settings app can reset credentials
  via com.android.credentials.RESET.
* com.android.credentials.INSTALL should still be
  callable by CertInstaller.

Manual testing steps:
* Install certificate via Settings
* Verify unable to reset certificates via test app
  provided in the bug (app-debug.apk)
* Verify able to reset certificates via Settings
* Verify com.android.credentials.INSTALL isn't changed

Bug: 200164168
Test: manual
Change-Id: I9dfde586616d004befbee529f2ae842d22795065
(cherry picked from commit 4c1272a9)
Merged-In: I9dfde586616d004befbee529f2ae842d22795065