Fix ctrl-s (screenshot window) does not work, #4822

[low-batt]

This commit will change the MPVController.mpvInitRendering method to enable advanced control when creating the mpv renderer context. Advanced control must be enabled for this variation of the screenshot command to work.

• I have read CONTRIBUTING.md
• This implements/fixes issue Ctrl-s (screenshot window) does not work #4822.

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Description:

[low-batt]

Rebased with develop and fixed merge conflicts.

[lhc70000]

I remember that it was disabled on purpose. We need to take a further look.

[low-batt]

YES, this change needs a close look. This was disabled as a fix for issue #2149. In digging through old mpv commits I thought I saw some mpv fixes that might have fixed the hang. I did confirm those fixes were made after this workaround was added. There is a lot of discussion in the associated issue.

We should definitely merge PR #4819 first (as long as that one passes review). This PR corrects many data races detected by TSAN by moving work off of the MPVController queue and on to the main thread. As a lot of that is small I thought it better to access the data only from the main thread rather than adding locks to coordinate access.