Move away from final field mutations

[syldium]

Implements #84. This also adds compatibility for Minecraft 26.2-pre4 as it changes the serializable team class (ClientboundSetPlayerTeamPacket$Parameters) to be a record, making final field mutation impossible.

The most significant change is that the ClientboundSetObjectivePacket packet is now constructed with a Objective NMS object. Instanciation of the ClientboundSetDisplayObjectivePacket and ClientboundSetPlayerTeamPacket classes has been adapted to prefer their constructors.

This change also involves changing how older versions create their packets, therefore requiring extensive tests against numerous versions. So far, it has been tested with:

• Paper's dev/26.2 branch, Java 26
• Paper 26.1.2, Java 26
• Spigot 1.13.2, Java 11
• Spigot 1.8.3, Java 8

[MrMicky-FR]

Hi,

Thanks a lot for this update! Tested on 1.7.10, 1.8.8, 1.12.2, 1.13.2, 1.16.5, 1.17.1, 1.21.1, 1.21.11 and 26.1 and seems to work perfectly 🚀

I was thinking of merging this once the 26.2 release drops, but open to doing it before :)

[MrMicky-FR]

Hi, 26.2 was just released, it seems to work fine, is this ready to release or more testing is required? Thanks!

[syldium]

It's ready for merge; I don't have any more changes planned.