Add `Download All` buttons

[jmgasper]

Description

Currently, there is not way for users and competitors to download Marathon Match submissions. This is an important functionality because these are for “Fun” and for learning purposes so being able to see other users' submission is valuable.

Enhancement requests:

Should be done already:

• Once the MM challenge closes,
  • When a user is on the “Submissions” tab of a Marathon Match, allow all logged in members to be able to select and download submissions.
  • When a user is on the “Winner” tab of a Marathon Match, allow all logged in members to be able to select and download winning submissions.

New requirements:

• Once the MM challenge closes,
  • Enable a Download All submissions button
  • Enable a Download All winning submissions button

Implementation

Branch

Please target the mm_download_submission branch

In browser

We need to implement the zipping in browser, preferably with a loading / progress spinner shown while the zip is being built.

Potential library option: https://github.com/101arrowz/fflate