### What?
Uses sequential pattern for Bulk Upload instead of `Promise.all`.
### Why?
* Concurrent uploads led to filename conflicts for example when you have
`upload.png` and `upload(1).png` already and you try to upload
`upload.png`
* Potentially expensive for resources, especially with high amount of
files / sizes
### How?
Replaces `Promise.all` with `for` loop, adds indicator "Uploaded 2/20"
to the loading overlay.
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Co-authored-by: James <james@trbl.design>
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