refactor: Rewrite applying extensions

[cgytrus]

Fixes the currently main 4.x issue

• disallows installing extensions outside of _init
  • same reason as below, allowing this would require restructuring my code again..
• removes runtime mod toggling/reloading
  • too complicated for me to implement with the rewrite and ive been told it was unstable anyway
• fixes preloaded scenes that refer to extended scripts not getting updated
  • if you have a scene that refers to a script, that scene gets preloaded and the script gets extended, the preloaded version of the scene would still refer to the old script, i believe the use of reload instead of new fixes that but i havent actually checked if thats true
• the rewrite ends up fixing these
  • fixes Several mods cannot extend the same script with a class_name #338
  • fixes Possible memory leak with script extensions #353
• supersedes fix: non-static func call on InheritanceSorting #363 (already merged anyway)

how this works:

• collects all extension scripts (no changes here)
• uses the base script as the original script that will be extended (no changes here either)
• copies the original script to a temporary directory on disk
  • it seems to be impossible to create a new file in the project otherwise and extends ignores resource cache, which is what take_over_path overrides, it reads only from packs or the file system
• extends in the extension scripts is patched to instead extend the script previous in the mod hierarchy, down to the copied original file
• the original script's source is overwritten with the source of the last applied extension
  • take_over_path didnt seem to work for this
  • the hierarchy ends up as mod (overwritten original) > mod > mod > ... > copied original
• all involved scripts are reloaded in backwards order (starting from copied original, ending with overwritten original)
  • this ensures that all the scripts are up to date with the patches and preloads and whatnot
• temporary directory together with all the patched extensions and copied original is deleted from disk as theyre now loaded and not needed anymore

i didnt test much, especially with dependencies, but for a simple use case of a couple mods this seems to be working
also please squash when merging lol

current issues:

• there seems to be an issue where this also ends up hijacking the paths in the debugger too, when you click on an extended script in a stack trace it opens files that were either already deleted from the temp folder or original files that had their source code replaced in runtime