Create a .zip file instead of triggering multiple downloads #65
Description
Chrome, Edge, and other browsers based on them limit the number of downloads a page can trigger at once.
Instead of downloading multiple files when we upload a FASTA file with several proteins, we should collect them into a single zip file that we then download.
This is the same issue as PGFinder has: Mesnage-Org/pgfinder#312 and the Fragment Generator in PGFinder already zips files, so that code can just be copied over!