feat: downloadStill from media pool

[Julusian]

About the Contributor

This pull request is posted on behalf of myself/Bitfocus Companion

Type of Contribution

This is a Feature

New Behavior

This adds the ability to download still frames from the media pool.

To support this, rle decoding and yuva422 to rgba colour conversion has been implemented too.

Testing Instructions

Other Information

Status

• [x] PR is ready to be reviewed.
• [x] The functionality has been tested by the author.
• [ ] Relevant unit tests has been added / updated.
• [ ] Relevant documentation (code comments, system documentation) has been added / updated.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 22.64151% with 82 lines in your changes missing coverage. Please review.

Project coverage is 83.61%. Comparing base (5e62374) to head (0a5abe0).

Files	Patch %	Lines
src/lib/converters/yuv422ToRgba.ts	5.12%	35 Missing and 2 partials :warning:
src/dataTransfer/dataTransferDownloadStill.ts	11.11%	23 Missing and 1 partial :warning:
src/atem.ts	15.00%	13 Missing and 4 partials :warning:
src/dataTransfer/index.ts	25.00%	3 Missing :warning:
...DataTransfer/DataTransferDownloadRequestCommand.ts	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #167 +/- ## ========================================== - Coverage 84.69% 83.61% -1.08% ========================================== Files 189 191 +2 Lines 5951 6055 +104 Branches 887 956 +69 ========================================== + Hits 5040 5063 +23 - Misses 911 960 +49 - Partials 0 32 +32 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.