Decouple processing logic from uploading itself

[swissspidy]

@mexp/upload-media won't have any upload logic, needs to be passed via settings

@mexp/media-utils only cares about uploading, like today. Doesn't have any state.

Also adds some initial file validation before the item is added to the queue.

See #561

[github-actions]

Size Change: +181 B (+0.01%)

Total Size: 3.02 MB

Filename	Size	Change
build/media-experiments.js	68.8 kB	+167 B (+0.24%)

ℹ️ View Unchanged

Filename	Size	Change
build/100.js	88.3 kB	0 B
build/699.js	2.35 MB	0 B
build/blurhash.worker.js	3.23 kB	0 B
build/canvas.worker.js	2.79 kB	0 B
build/chunk-ffmpeg.js	5.91 kB	0 B
build/chunk-selfie-segmentation.js	16.3 kB	0 B
build/dominant-color.worker.js	4.45 kB	0 B
build/ffmpeg.js	1.1 kB	0 B
build/heif.worker.js	422 kB	0 B
build/media-experiments-blocks-rtl.css	297 B	0 B
build/media-experiments-blocks.css	296 B	0 B
build/media-experiments-rtl.css	885 B	0 B
build/media-experiments.css	885 B	0 B
build/pdf.js	578 B	0 B
build/subtitles.js	848 B	0 B
build/view-upload-request-view-rtl.css	716 B	0 B
build/view-upload-request-view.css	717 B	0 B
build/view-upload-request.js	17.2 kB	+14 B (+0.08%)
build/vips.worker.js	42.6 kB	0 B

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