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[bot]]

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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