Add connected displays to appropriate power group

- Sort displays into appropriate power (display) groups
- Determine this based on desktop content mode.
- Ensure that, if a group with this type of display already exists, the
  display is added to that group.

Bug: 402406603
Flag: com.android.server.display.feature.flags.separate_timeouts
Test: adb shell dumpsys power | grep group.*user -A15 -i
Test: adb shell dumpsys display | grep "Display Groups" -A15
Test: confirming that I ran CD smoke tests

Change-Id: I8663659de156f9ab2b8e9049fd212aae6e278195