[Java] /coordinate query command

This command could be used to return the coordinate of the current context (and write it to e.g. a score using /execute store). Currently, the only way to achieve this is to create an entity and reading its position.

In conjunction with the new /execute on command, this could be used to write a heightmap coordinate into the scoreboard, or in case of executing at an entity, this could be a more efficient way to read a coordinate without needing to read NBT.

Proposed syntax:
/coordinate query (x|y|z)

or possibly:
/coordinate query (x|y|z) [scale]
To also read decimal places with scale.