MES - Moog's End Structures

Added

• Added 3 custom End loot tables (end_common, end_uncommon, end_rare) and applied them to all structures
• Filled empty barrels in the Deepslate Mega Ships with loot

Fixed

• Removed a broken template pool from the Crashed Deepslate Mega Ship that referenced NBT files which don't exist

Changed

• Consolidated all mega ship NBTs from versioned folders (v1_21_0_4, v1_21_5_10) into a single mega_ship/ subfolder as files were identical across versions
• Removed versioned pool elements from all mega ship pools except mega_ship_deepslate_2/side_pool (which still needs versioning for the chain -> iron_chain rename in 1.21.9)

Removed

• Removed 18 unused loot table files that were leftover from earlier development