Extend echem block to allow rendering cycling metadata from mps file

[ml-evs]

We should add the ability to use https://github.com/the-grey-group/mps_parser (once finished) to display cycling data alongside the .mpr. One route could be automatically grabbing/scraping any <name>.mps file if <name>.mpr exists.

[jdbocarsly]

More generally, we will need the ability to attach multiple files to a block. I would also like to move the file upload prompts into each individual block rather than being at the top of the item (I think).