fix(ecosystem): Breaks issue sync cycles

[GabeVillalobos]

The problem:

When a Jira issue's assignee field is quickly modified multiple times in a row, we end up assigning and resyncing the assignees to Jira, which causes a loop. This is because all inbound integration webhooks that modify an issue assignment generate an outbound update for all issue sync integrations as well.

Solution:

This PR adds a new AssignmentSource dataclass, which acts as a context carrier when an external webhook triggers an issue assignment change. This is then checked on the outbound sync logic, preventing the change from being propagated to the same integration that initially triggered the change.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

:white_check_mark: All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #77754      +/-   ##
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+ Coverage   78.11%   78.15%   +0.03%     
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  Files        7082     7092      +10     
  Lines      312250   312829     +579     
  Branches    51010    51105      +95     
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+ Hits       243910   244478     +568     
+ Misses      61984    61964      -20     
- Partials     6356     6387      +31