Camera: Add AE priority mode tags

- Add AE priority mode tags
- Populate CONTROL_AE_AVAILABLE_PRIORITY_MODES with at
least OFF mode

Test: Camera CTS with and without flag
Bug: 359944765
Flag: com.android.internal.camera.flags.ae_priority

Change-Id: I1aec82f212915d6ddbd0e6f55b015a0d840b2585