The task is to do some clean up on the authorization test package structure.
1. Move AuthorizatioinTest.java and AuthorizationStmtTest.java to authorization test package.
2. Rename CustomClusterGroupMapper and CustomClusterResourceAuthorizationProvider to TestSentryGroupMapper and TestSentryResourceAuthorizationProvider since those two class aren't specific to custom cluster anymore.
3. Move those two files into `testutil` instead since they're not actually test classes.