Modernize Buildscript + Misc. Changes

[solonovamax]

Modernize the buildscript with the following changes:

• Use kotlin buildscripts instead of groovy buildscripts
• Use convention plugins to split configuration away from main buildscript
• Add several dependencies:   - fabric language kotlin: kotlin libraries   - cloth config & modmenu: config   - patchouli: in-game documentation   - slf4k: nicer logging w/ slf4j in kotlin
• Add access widener
• Move versions to libs.versions.toml
• Clean up some misc. conventions

Misc. changes:

• Add .editorconfig
• Update .gitignore
• Update .gitattributes