Cleanup: Move Permission handling out of DevicePolicyManagerService

Moving this logic to a helper class reduces the size of DPMS, while also
improving encapsulation.

BYPASS_LARGE_CHANGE_WARNING: This CL mostly moves a lot of code around.
Test: CtsDevicePolicyManagerTests
Flag: EXEMPT refactor
Bug: 433711377

Change-Id: If44a13c88540f32577f44f988730354bd187082c