Refactor versions, resources and assets

This MR refactores a ton of stuff

Refactores:

• Versions
• Assets

It also improves the performance (but increases the memory usage)

ToDo:

• Assets per version
• zstd compression (reminder: pixlyzer is already in mbf format (probably zstd compressed))
• eros: Download/progress dialog
• Features (like disable audio)
• Save as hash (do not save duplicated)
• GUI assets manager (pre download assets, show downloaded versions; remove version data)
• Assets verification (with size, hash, download missing ones)
• Resource packs
• Assets reloading
• minecraft skins, capes
• server resource packs
• integrated data as "optional resource pack"
• Resource pack fixes
• Documentation on how to use resource packs

Fixes #48 (closed)