[likes] reduce performance impact, add count and recent likes

[luceos]

Fixes #0000

Changes proposed in this pull request:

This PR supposedly adds two new values by default to each post whenever Likes is enabled. A count of likes and the most recent likes.

I ran into an issue with the count, but before I spend much more time on this let's figure out whether we want this at all.

(I know dist needs to be removed :) )

Reviewers should focus on:

Screenshot

Necessity

• Has the problem that is being solved here been clearly explained?
• If applicable, have various options for solving this problem been considered?
• For core PRs, does this need to be in core, or could it be in an extension?
• Are we willing to maintain this for years / potentially forever?

Confirmed

• Frontend changes: tested on a local Flarum installation.
• Backend changes: tests are green (run composer test).
• Core developer confirmed locally this works as intended.
• Tests have been added, or are not appropriate here.

Required changes:

• Related documentation PR: (Remove if irrelevant)
• Related core extension PRs: (Remove if irrelevant)

[clarkwinkelmann]

I know it's still a work in progress, but just reading through the code I notice the isLiked part in addLikeAction is not updated with new code yet.

[luceos]

Yeah. We still need to decide whether we want this and if we do, finish it.

[SychO9]

Superseded by #3781