feat: process rfc-editor queue notifications from purple

[rjsparks]

This adds an endpoint that accepts a post of the queue json and passes it to a celery task which updates all of the documents in the queue (and those that had been in the queue but no longer are) accordingly.

It follows similar logic to the old queue processor, but changes things so that only two new draft-rfceditor states are used: in_progress and blocked. It adds a new DocEvent derivative RpcAssignmentDocEvent that captures, in text form, roughly what the new queue site shows in its Status column.

Note well that the first time the new queue is processed, any documents with old draft-rfceditor states will be updated to the new states and the new status values will be added as an RpcAssignmentDocEvent, leading to a pair of email messages to each subscriber using the community tool to watch for changes to the document. At the time of development slightly more than 4000 messages would have been emitted.

Claude was used heavily in the creation of this PR.

[codecov]

Codecov Report

❌ Patch coverage is 98.92473% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 88.49%. Comparing base (473bbb2) to head (45062c5).
⚠️ Report is 8 commits behind head on main.

Files with missing lines	Patch %	Lines
ietf/sync/tasks.py	98.52%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##             main   #10857    +/-   ##
========================================
  Coverage   88.49%   88.49%            
========================================
  Files         332      332            
  Lines       44851    44973   +122     
========================================
+ Hits        39690    39801   +111     
- Misses       5161     5172    +11     

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[jennifer-richards]

Looks generally good. A couple nits (one just an aesthetic suggestion, disregard if you prefer). A couple questions about tests, including several about a state that I don't think is valid in the queue json input.

[jennifer-richards]

Again the "state": "blocked"

[jennifer-richards]

Looks good. The tests are a little oddly organized / named but they cover the necessary cases.

[jennifer-richards]

Waiting for compatibility testing with purple's side of the API before merging