Fix flatlines on exit

[Roms1383]

See previous PR #18's description for all the details: it's restarted from scratch to reduce unnecessary changes.

[Roms1383]

So to resume for future myself who will have completely forgotten about this (and other persons interested):

• macro crate should not contains any dependency to RED4ext related crates (e.g. red4ext-rs) 🦺 it can mess up with linker and cause unexpected UB, and generated code does not need it since it's string
• native plugin unload is called after ScriptableSystem.OnDetach / GameSession/BeforeEnd / GameSession/End 🦺 native plugin code must not call any Redscript function back after e.g. GameSession/End, otherwise it flatlines if e.g. game is exited abruptly from Windows task tray bar
• wref must be used instead of ref in specific cases after latest libs update (inside UI, when interacting with TweakDB) 🦺 this can also cause the game to flatline on exit

[Roms1383]