Add ViaVersion Support

[erenkarakal]

Description

This PR adds ViaVersion support to ExprPlayerProtocolVersion. If ViaVersion is not installed on the server it defaults to the current one.

Why?

The current expression only returns the server's version, not the player's.

To sum up the discussion on discord and my opinions

It was recommended to use reflection as it was deemed unnecessary to have another dependency while compiling the jar. While this goes against the code conventions of Skript as it may not be future-proof, I would like to point out that the ViaVersion API hasn't been changed in the last 3 years (at least getting the player's version), and 3 years ago only the package name was changed.

Another thing that was brought up was "stuff related to other plugins shouldn't be in Skript". Even though I agree with this, I don't think there is another solution right now. So even if this PR doesn't get merged, I propose that we rename or remove this expression because it is straight-up misleading.

---

Target Minecraft Versions: any
Requirements: none
Related Issues: none

[sovdeeth]

My opinion is that ExprPlayerProtocol version should be changed to an event-value in the server list ping event. That's the only time the version number ever differs from the server's, and hence the only time it's ever useful.
As far as viaversion support, this feels like a great thing for an addon to support.

[Moderocky]

I don't like building around other plugins in principle, but in this case I'm not particularly against the change since it's a pretty good use case.

[Moderocky]

Good it looks better now

[sovdeeth]

Request for more reviews/opinions

[cheeezburga]

Suggested change

	if (Skript.classExists("com.destroystokyo.paper.network.NetworkClient") || viaVersionExists) {
	register(ExprPlayerProtocolVersion.class, Integer.class, "protocol version", "players");
	}
	if (Skript.classExists("com.destroystokyo.paper.network.NetworkClient") || viaVersionExists)
	register(ExprPlayerProtocolVersion.class, Integer.class, "protocol version", "players");