Make stream recorder work concurrently

[uvjustin]

Proposed change

The current stream recorder works by spawning a recorder worker thread from the RecorderOutput.cleanup() function once the intended duration is reached and the RecorderOutput is removed. Since the worker is not called until the end of the recording, the video data is retained in the RecorderOutput until this time, and the work to remux the video is done all at this time.
This PR changes the async_record call to use a new RecorderOutput.async_record method which processes each segment in real time (farming the actual muxing work out with executor thread tasks). This may reduce the memory usage for longer recordings of several minutes or more, and it may also allow for recovery of a partial file in case there is an interruption to HA during the recording.

Type of change

• Dependency upgrade
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[probot-home-assistant]

Hey there @hunterjm, @allenporter, mind taking a look at this pull request as it has been labeled with an integration (stream) you are listed as a code owner for? Thanks!
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[allenporter]

This is a great improvement! Really like the idea of writing the stream as soon as possible rather than buffering the entire recording.
I have hust a couple questions about the core of the worker loop.

[uvjustin]

I put this part in (writing to a file with a different name first) because I believe some users currently use the existence of the output file to check whether the recording is done yet.

[uvjustin]

Rebased on dev