Add `upload_rm` file transfer option (rebased onto develop)


This is the same as gh-2777 but rebased onto develop.

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Similar to `ln_rm`, this first performs a remote upload
and then deletes the file locally if the upload and hash
check were successful.

/cc @mtbc Suggestion from Paris.
@gusferguson was still thinking about better names.
@ximenesuk pointed out that *this* would have been the appropriate place for "transfer"