Rewrite Uploader to use fs-capacitor #3098

This allows for upload to start almost immediately without having to first download the file.
And it allows for uploading bigger files, because transloadit assembly will not timeout,
as it will get upload progress events all the time.
No longer need for illusive progress.
Also fix eslint warnings and simplify logic

Still TODO: TUS pause/resume has a bug:
tus/tus-js-client#275