Support Evaluate Request

[skess42]

The Request evaluate is used by watch expressions, which could be useful to evaluate several things:

• Scores (maybe with a syntax like score @e[tag=some_tag] some_objective)
• Tags (maybe with a syntax like tags @e[type=player])
• NBT values (maybe with a syntax like nbt @e[tag=some_tag] some.nbt.path)

It is also used by the REPL feature of the Debug console, which could be useful for:

• Teleporting the player to the current execution position.