Add resume feature for download.

[Ranjul-Arumadi]

What's the problem this feature will solve?

I had to install a 355 MB package for Rasa and upon reaching about
80% download completion my network was lost and I had to restart the whole download .Considering the poor connectivity many of the people living in poorly connected ares have to endure ,I think something has to be done about this.

Describe the solution you'd like
I think devising a mechanism that can break down the total download into mini downloads can resolve this issue. Also giving the user the option to determine the size of those mini download packets and well as the number of mini packets can help.

By giving the user the option to set the number of packets as well as the size of the packets can help the individual save the data as well as time it would take to download the remaining files if in case they lost their network or had to shut down their system for some reason.

Alternative Solutions

If the feature of providing the user the option to determine the number and size of downloads is difficult , pip could maybe
by default set any download file with size above for example 0.5 GB to be split into multiple downloads rather than one single download.

Additional context
Screenshots of my issue attached below.

[McSinyx]

Hello there, you might want to join the discussion at GH-4796.

[uranusjr]

Closing as duplicate to keep discussions in one place.