feat: Add attribute syncing

[WiIIiam278]

Closes #219. Closes #249.

Adds support for syncing attributes applied to players, including modifiers and instances and fixes issues related to health and max health syncing.

The following data values which can be attributed to the player will now be properly synced:

• Flight speed
• Movement speed
• Luck
• Knockback resistance
• Mob pathfind follow range
• Knockback
• Attack speed
• Max absorption (1.20.2+)
  This means that plugins/commands modifying player attributes directly will now be correctly synced cross-server. This system now also better takes into account modifiers from equipment and potion effects.

This also futureproofs support for syncing these newly customizable values coming in 1.20.5/1.21:

• Block breaking speed
• Entity/block mining range ("reach")
• Step height
• Jump strength
• Distance you can fall without taking fall damage
• Fall damage calculation multiplier
• Gravitational pull