Add setting to force transcoding above a max resolution (#1955)

## Description
Adds a new setting to pick a maximum resolution (by height). Any
playback that has a larger resolution will be transcoded down to the
maximum resolution.

Playback equal or less than the maximum resolution will not be affected
and will direct play if otherwise able. This setting is also independent
of the maximum bitrate (ie if max resolution is 4K and max bitrate is
2mbps, playing 4K will transcode).

This setting is pretty much equivalent to the Web UI setting "Maximum
Allowed Video Transcoding Resolution" with "Limit maximum supported
video resolution" enabled.

Note: this setting does not affect which version is chosen by default

### Related issues
Closes #756
Closes #1594

### Testing
Manual emulator testing

## Screenshots
N/A

## AI or LLM usage
None

app/src/main/proto/WholphinDataStore.proto

@@ -57,6 +57,7 @@ message PlaybackOverrides{
   bool direct_play_dolby_vision_e_l = 6;
   bool decode_av1 = 7;
   AssPlaybackMode ass_playback_mode = 8;
+  int32 max_resolution = 9;
 }
 
 message PlaybackPreferences {