manual DVR -auto restart recording after unintended instances of recording stop

[pitts-mo]

It is desirable for manual recording to automatically start again after a mode change, camera switch, or other instances of unintended recording to stop.

Suggest track users desired DVR recording state. Then automatically start a new DVR recording if DVR stops while users recording state is still ON.

Users manual DVR recording state should default OFF at boot.

[RaceMiata]

My upcoming commit(s) will be a good base on code change for your request.

I'm working on DVR start/stop logic overhaul. I just had a pull request ready to merge to fix DVR start/stop logic from ELRS backpack DVR controls PR #594 as a first step of my much bigger overhaul work in progress.

I'm about to make another PR (or perhaps new commits on the same PR) with 2 new flags record_pending and sdcard_ready. They'll be used to restart DVR automatically for whatever happens to the SD card being not ready (e.g. error writing file, SD card eject/re-insert), and more importantly facilitate user to toggle DVR on even before the SD card is ready (e.g. on bootup, after re-insertion).

The reason I want to be able to toggle on DVR before SD card ready on bootup is that sometimes I have to reboot goggle for whatever reason when other pilots are ready at a race round. Judging solely by the "sd card inserted" OSD icon turning off doesn't mean the SD card is ready. I had to wait til the SD card repair process to finish (no indication on OSD) before I could start DVR and tell race director I'm ready. Otherwise, if I toggle on DVR before the SD card is ready then DVR will never start.

With the new feature I can just toggle DVR on and tell race director ready and the DVR will start when the SD card repair process is finished.