Export Tools for GameTest

Hello! In light of the fact that Mojang is making a lot of their debugging tools available to the public and removing code obfuscation, I would like to suggest a change to the GameTest utilities.

In Java Edition, there is code for export sub-commands in "/test" and an "Export Structure" button in the Test Instance Block. These can be used to export strutures to SNBT files. These files can be loaded across different worlds using Structure Blocks and the "/place" command.

However, due to the way the functionality is coded, this feature can't be enabled without modifying the game. Having access to these export tools would be very useful, as it would allow content creators to easily load/place their structures across different worlds.