Update to .NET 8

[Wartori54]

Draft PR since we need to fix a few things still.

Necessary:

• Update NLua submodule/get the pr merged and switch to a package
• Verify that there is no floating point differences with the upgrade (basically run a long TAS)
• Fix code mod building targeting a .NET 8 everest

Good to have but not strictly required:

• Wait for an updated package for MonoMod.Patcher and MonoMod.RuntimeDetour.Hookgen to ditch the submodule
• Relinker rewrite
• Find a solution for old MacOS (or just not care about it) (update: game booted in a vm)
• Make piton delete the old runtime (.NET 7) on upgrade Turns out it will be overwritten

I should note here that I upgraded the other nuget packages, since we might as well do it :P

[Wartori54]

Closed in favour of #827 and #828.