Update for Minecraft 1.21 compatibility

[AramLR]

This pull request addresses compatibility issues with Minecraft version 1.21. The following changes have been implemented:

1. Updated generator.js and gen_new.js to create a pack.mcmeta file with pack format 48, which is compatible with Minecraft 1.21.

2. Modified the folder structure to align with Minecraft 1.21 changes:

   • Renamed the 'functions' folder to 'function' (singular) to match the new naming convention.

These modifications should resolve the majority of issues encountered when using this tool with the latest Minecraft version.

Changes made:

• Updated pack format in pack.mcmeta to 48
• Renamed 'functions' folder to 'function' in generated structure
• Adjusted file paths and references accordingly

Testing:

• Verified tool functionality with Minecraft 1.21

[Dyljyn]

@Stevertus could we move this pull request forward?