Add filters and sorts for communities page

[jordan1776]

Requirements

• Is this a feature request? For questions or discussions use https://lemmy.ml/c/lemmy_support
• Did you check to see if this issue already exists?
• Is this only a feature request? Do not put multiple feature requests in one issue.
• Is this a server side (not related to the UI) issue? Use the Lemmy back end repo.

Is your proposal related to a problem?

On the communities tab, it can be hard to look for certain communities, especially if they are on another instance. If I only have a slight idea of what I'm looking for (don't know what the name should be), I would have to scroll though every community on "all" which is very time consuming.

Describe the solution you'd like.

Filters:

• Instance (Dropdown list of all federated communities, shown on all)
• NSFW (Exclusively show/remove communities which are on instanced that allow NSFW, shown on all)
• Not subscribed (Remove subscribed from all and local)
• Language/country
• Federated with (Remove communities in instanced, the home instance is defederated from)

Sorts:

• Allow clicking on Subscribers ,Users / month ,Posts ,Comments headers to sort largest to smallest. and click again for smallest to largest. 
• Maybe include a header for date created to see newly made communities? And one for date last posted to for finding active communities?
• Also date added header in the subscribed.

Describe alternatives you've considered.

I could use browse.feddit.de , but it doesn't automatically format the links to my home instance, The /search page set to communities and search term " " doesn't do what I am trying to do (and not very intuitive).

Additional context

Adding more headers might make the table too wide, so possibly having an option in settings to check which headers the user wants to see might be a good thing.

[mpusch88]

Being able to sort by the column headers in the community list seems mandatory

[jordan1776]

It looks like someone else brought it up in issue #1177 which is for adding sorting to column headers is being worked on (#1538). It appears there was a bug #3374 in the backend which needed to be fixed (#3376) which delayed progress on that.