[WIP] Add backend support for muting communities

[kartikynwa]

Fixes https://github.com/LemmyNet/lemmy/issues/3160

Adding backend support for muting communities in this PR.

The database schema and API are identical to that for blocking of communities.

Communities are muted/unmuted via /api/v3/community/mute endpoint and the request structure is identical to /community/blocking:

curl -i -H "Content-Type: application/json" -X POST \
  -d "{"mute": true,  "auth": "...",  "community_id": 3}" \
  "http://localhost:8536/api/v3/community/mute"

Where muting differs from blocking is that it only affects listing of posts when ListingType in PostQuery is All or Local and all of community_id, creator_id and search_term are not provided. Plus PostQuery takes an optional value show_muted. When this value is Option<true>, posts from muted communities are never hidden. I have tried to be conservative with making changes to default API behaviour which is why as things currently are, only the default output for /c/all and /c/local would be affected.

TODO

• [ ] Have to update the API documentation but don't know how to do that yet.
• [ ] There is a lot of code duplication from the community blocking. I am not sure how to modularise. Advice for it is welcome.
• [ ] I don't understand the changes I made in the apub crate. I implemented the SendActivity trait so that compilation succeeds and I can test the changes locally. ActivityPub spec does not mention muting so not sure what to do here. Help appreciated.
• [ ] Have to update tests for post_view.rs

[Nutomic]

This is already implemented as /api/v3/community/hide

[kartikynwa]

@Nutomic hiding seems to be something that admins do. Like they can hide a community so that it doesn't appear on the front page for every user.

This PR is per user configuration like blocking. I can mute a community so that it does not appear in the all feed for me but continues to appear for other users (unless they choose to mute it too).

[dessalines]

I still don't fully understand the difference between community blocking and muting. If I don't want to see a community, why not block it?

[kartikynwa]

Blocking precludes you from interacting with the community in any way. If you mute a community, you can either visit it manually or follow a link to a post in that community and leave a comment there or vote if you want. It just won't appear in your feeds.

[dessalines]

To be more clear then, this should be hide_from_feeds or hide_from_all_and_home . It wasn't clear to me and I'm sure it won't be to others.

[Nutomic]

Blocking precludes you from interacting with the community in any way. If you mute a community, you can either visit it manually or follow a link to a post in that community and leave a comment there or vote if you want. It just won't appear in your feeds.

I think theres an open issue about allowing you to browse a blocked community if you explicitly navigate to it, or view a post inside it. I think that would be a reasonable solution and it wouldnt require yet another setting.

[kartikynwa]

That does sound like a better solution to me. I'll look into that and close the PR in a while.