Allow contacting participants for ID validation

Is your feature request related to a problem? Please describe.
When an ID document is invalid, there is no way to contact participants to explain them the reason of the reject.

Describe the solution you'd like

1. When rejecting an ID add a text field to send an explanation to the participant by direct message (like in proposals).
2. (optional) Allow to relate the ID verification to the participant profile.

Describe alternatives you've considered
Right now when an ID is badly scanned, we have to scan and guess among all participants, accounts that are likely to match the faulty ID request, and then send a private message to all the likely participants. Sometimes googling the participant name, may provide a faster way to establish a direct contact (through a personal website, FB or Instagram, etc) but this is not a robust solution and it is an intrusive one.

Does this issue could impact on users private data?
Feature 2, is probably not available in DECIDIM by design for good reasons, e.g. to avoid revealing the link between pseudonym and the real ID. Feature 1 solves the problem without having to reveal the ID.