Fabric: use Lucko's Fabric Permssion API

[CamperSamu]

This is an implementation of what is described in the issue #117.
This PR also updates the module to 1.21.

[CamperSamu]

(the force-push was to remove a useless commit related to a non-working fix)

[CamperSamu]

I am still testing this, wait before merging

[creatorfromhell]

I am still testing this, wait before merging

You can mark the pr as a draft.

[Revxrsal]

Status?

[CamperSamu]

@Revxrsal Tomorrow I should get some time to work on this.

[CamperSamu]

I've added a test mod for Fabric.
I've tested the behavior of the new Permission API with and without LuckPerms and it fallbacks to Vanilla correctly.
The default Vanilla permission level is 4 (OP), while it is required to include a permission string for good practice so that if a server has luckperms permissions are available.
If required, a command can be marked as available by default by setting the Vanilla level to 0.

[Revxrsal]

Thanks! I've merged it. What's the least supported version of Fabric though after this update?

[CamperSamu]

No problem, sorry for the delays and general slowness but life is getting me hard...
The supported version by the lib is now 1.21, but I think that something can be worked to bring a 1.8 - 1.21.4 support window via Forgix or by using the same trick that ViaVersion uses.

I'd love to work on it but I really don't know if I'll get the time to build something stable.
What I can advise is to keep the Fabric version always updated to latest.

[Revxrsal]

I'm not interested in maintaining Fabric support for versions older than 1.20 anyway, so I'm fine with its current state.