Make MRF and Quarantine work with tuples

This is for be-mr pleroma!2964 (closed) and issue pleroma#1850 (closed)

The idea is to also give a reason instead of only a list of rejected/muted/etc. instances.

Most of the changes are done in the BE, but some are done here.

• Change in the admin-fe to make tuples properly work for MRF and Quarantine
• Give other names to 'Key' and 'Value'
• Backwards compat (This version should still work on an old pleroma)

Example