New Action to enable bulk download of Project output files

[mjherzog]

When working with many Projects for a product it would be very helpful to enable bulk download of output files.
A reasonably intuitive approach would be to:

• Check the box for the Projects for which you want to download the output files
• Use a new Action to download output files for all of the selected Projects - ideally in a Zip or other archive format.

Since we have many output formats we could pilot this with XLSX output first and add the other options later if that is significantly easier.

[tdruez]

v1 implemented in #1517