feat: per-slot Turn in the camera settings, H.264/H.265 turned by the decoder (#201)

[compot-dev]

Part of #201. Version 2.18 (2.17 is #220).

• Turn in the camera settings (Auto, 0°, 90° ↺, 180°, 270° ↺), stored per slot; Auto keeps the URL's ?rotate= and the toys' defaults.
• H.264/H.265 are turned by the decoder (MediaFormat.KEY_ROTATION, Android 6+), MJPEG by the hardware JPEG decoder the same way, or while drawing on the software path. ?rotate= now works for every codec.
• The single view fits the turned size (a quarter turn swaps the sides); grid cells fill the cell as before.

Checked on Aceline-1: 90° on a 1080p H.264 camera in the single view (shown 1080×1920, pillarboxed) and in a grid cell; the settings dialog works with the remote and touch. The turn costs no frame rate there.

Not done yet:

• Mirror: setScaleX(-1) on the SurfaceView does not mirror the picture on the AG-216, so it is left out; mirroring a hardware decoder's output needs a GL path.

• Snapshots/screenshots: the debug snapshot of a turned slot came out turned by 180° in a test; it looks like PixelCopy already applies the decoder's turn, so the extra turn in Snapshots (this PR) is probably wrong. To be checked once more and fixed before un-drafting.

• Snapshot and long-press screenshot follow the turn

• Aceline-1: 0/90/180/270 in the single view and the grid