Hide outdated comments

[Kobzol]

To declutter PRs a bit, it would be nice if bors had a system for hiding old/not relevant comments:

• Once a PR becomes mergeable again, we could hide old comments about mergeability (Do not enable LLD by default in the dist profile rust#143255 (comment))
• Once a PR build finishes, we could hide the "Try/Auto build started" comment.

[JerryQ17]

rla is able to hide outdated comments (link), we can reuse that logic.

If no one is working on this, I would like to have a try. I'm not familiar with GraphQL, so it'll take some time for me to complete it.😁

[Kobzol]

Triagebot also has similar logic. It would be great if we can do it without GraphQL, but maybe it's the best way.

We can either remember the node IDs of comments that we sent, along with some metadata, or we can scan comments on the PR from GH API. But the latter could be quite exppensive, not sure if there's a way to find comments by a specific author through the REST API.

[JerryQ17]

Triagebot also has similar logic. It would be great if we can do it without GraphQL, but maybe it's the best way.

I think it's the only way. I can't find a REST API to minimize a comment.

We can either remember the node IDs of comments that we sent, along with some metadata, or we can scan comments on the PR from GH API. But the latter could be quite exppensive, not sure if there's a way to find comments by a specific author through the REST API.

The node id is required to minimize the comment anyway, remembering it will make the impl simpler.

If we scan comments to get those posted by bors (either by a REST API or manually filter with GithubRepositoryClient::is_comment_internal), it's still difficult to determine which comment to hide from its contents. Maybe the metadata in <!-- homu: {} --> will be useful.

[Kobzol]

We could use the metadata, but if we need the node ID anyway, then remembering it in the DB is a better idea anyway.