Add synchronization of remote featured tags

[noellabo]

Add function to sync remote account's featured tags.

Currently, the collection of featured tags is cached for 3 minutes, so if you deliver an Update activity immediately after an update, the update may fail. The load to deliver Update activity every time a featured tag is added or removed can be heavy. So, schedule it to be delivered in 3 minutes.

For updating, we can also introduce a method using the add/delete collection activity. What do you think?

[Gargron]

Is it unavoidable to add a new featuredTags collection and store its URI? I remember we wanted to put the tags into the featured collection alongside pinned posts, but back then there was some compatibility issue. Still think it may be more in the spirit of ActivityPub to have these objects in the same collection.

[noellabo]

I see, it would be better to put them together in a featured collection.

[noellabo]

Changed featured_tags_collection_url so that it is used on a ad-hoc basis instead of being stored in the database.
No more database migration is needed.

Add support for cases where the featured collection contains both Note and Hashtag.

However, in versions prior to Mastodon v3.5.1, an exception occurs, so feature collections containing both notes and hashtags are not read correctly.
see: #17964, #11595

For the time being, you should continue to use the featured tags collection.
We should also provide patches to other ActivityPub implementations in advance to solve the federated issues.

[Gargron]

I am so sorry. I forgot I made featuredTags back in 2020.

[noellabo]

This pull request will make the following changes

• Fetch and sync featured tags from featuredTags when processing remote accounts
• Deliver Update activity for actors when adding or removing featured tags
  • The collection response is set to cache for 3 minutes. To avoid this effect, the delivery is delayed by 3 minutes.
• (Update: Deliver Add / Remove activity when adding or removing featured tags.)
  • Add featured tag add/remove activity handler #19408
  • Change featured tag updates to add/remove activity #19409
• In the future, when the collection provided in the featured contains both Note and Hashtag (status and featured tag), we will be able to handle this
• The response of the instance API will now contain the status and featured tags. return the maximum number of featured tags in the instance API response

configuration: {
  accounts: {
    max_featured_tags: 10
  },
},

[ykzts]

https://app.circleci.com/pipelines/github/mastodon/mastodon/62811/workflows/19995830-c559-4126-ad38-1d6205091cb2/jobs/242348 🤔

[ykzts]

If CircleCI is enabled in the forked repository, I cannot check the results from the Checks tab of the Pull Request. We need to check the results in the CircleCI web UI of the forked repository.

[noellabo]

Okay, I see why. Thank you!