Paint's Piston Helper

Changes since v1.1:

* Updated /item command syntax so it works in 1.17 release, not just the 1.17 snapshots.
* Replaced summon area_effect_clouds with marker entities. This changes nothing but it might be slightly less laggy.
* Glazed terracotta will glow purple if it will be moved instead of white to show that it has unique unpullable properties.
* Fixed a bug where jammers (obsidian/bedrock/etc.) and collapsers (pumpkins/melon/etc.) would cause slime blocks and honey blocks immediately below them to not glow if they were being moved horizontally.

Reminder: You should NOT unzip the file, it works as-is.