Any plans to implement file upload progress?

[TAProgramming]

Hello,

I think having a file upload progress callback is an essential feature, especially considering many users will have varying internet upload speeds and may thing that the upload is stuck.
I have a continuous loading animation, but that doesn't show real progress of the file upload.

If it's not impossible, please could you consider it. I may try to contribute if no one is interested, but being a front end developer it may take some time for me.

Thanks. :)

[didierfranc]

Rest and especially fetch which become the new standard, doesn't implement a way to do that ...

[dplewis]

Closing via #373