Downloaded snapshot filename should include id/date rather than just snapshot.json

[knolleary]

Description

The 'download snapshot' feature always downloads the snapshot as snapshot.json. It would be better to have a a more unique name so you don't end up with snapshot.json, snapshot (1).json etc.

One option would be to include the snapshot name in the filename - but with our auto-generated names, that could get unwieldy.

Propose something like: snapshot-<id>-YYYYMMDD.json

Epic/Story

#3627

Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate