Makes withdrawing a request semantically distinct operation

[allanlasser]

Fixes #575

Previously, we conflated withdrawing a request with rejecting, which led to some unexpected behavior. This is now clearer, with a specific ability to understand what happened to a particular request.

Note: currently based on #582 to avoid migration merge conflicts. Should be rebased and merged following that change.

[duckduckgrayduck]

I requested to join Allan test org, withdrew my invitation, but it still appears to to hide the Request to Join from me. Says "Your request to join this organization was rejected. Please contact an admin if this is a mistake and you need to be added to this organization"

[allanlasser]

I requested to join Allan test org, withdrew my invitation, but it still appears to to hide the Request to Join from me. Says "Your request to join this organization was rejected. Please contact an admin if this is a mistake and you need to be added to this organization"

I'll have to double check our context data and template. Thanks for catching this!

[allanlasser]

@duckduckgrayduck found the issue—I needed to update the form action from "reject" to "withdraw" in two locations. Should work as expected now!

[duckduckgrayduck]

That is fixed, however the withdrawn request still appears in the list of pending requests at /organizations/ and under the "Open Requests" section of my profile I think because it is checking if these are rejected or accepted, not handling the withdrawn case.

[allanlasser]

Great, fixed that one too—two missing lines in our User model.