fix(filters): keep directly-addressed notifications when excluding by author

[afonsojramos]

An author: exclude filter was hiding review_requested, assign, and mention notifications when a bot (such as coderabbitai) merely left the latest comment, because enrichment sets subject.user to the last commenter. The exclude now skips notifications whose reason means the user was directly asked to act (approval_requested, assign, mention, review_requested, team_mention), while still filtering passive bot comment noise (subscribed/comment). The exemption is scoped to the author: qualifier and to excludes only, so include, org:, and repo: filters are unchanged. Adds regression and unit tests covering the new behaviour.

Closes #2914

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[setchy]

I've been thinking about this FR...

GitHub UI doesn't distinguish between author or commenter, since notifications always show the latest state - so I was tempted to close the FR as unplanned...

That said, alternatively, we could look to change the filter include/exclude tokens to support author: and commenter: prefixes which could search on the two different user attributes.

I'm not sure I'm a fan of changing the filter based on the notification subject code

[afonsojramos]

@setchy fair... It is also forge specific code that is leaking A LOT tbh