This adds:
- LuaCsSetup.ExceptionHandler so we can decide how we want to handle
exceptions for unit tests
- LuaCsSetup.MessageHandler so we can redirect logs to the XUnit output
helper
This completely changes how method patching works under the hood. Unlike
the previous API (`Hook.HookMethod`), the new API (`Hook.Patch`)
generates a Harmony patch method at runtime, using IL generation.
This fixes methods with ByRef (out/ref) parameters getting silently corrupted
due to the ByRef semantics being lost when passed through the `object[] __args`
parameter.
This new API also makes it possible to:
- modify parameters (including ByRef params)
- change the return value to `null` (old API would use `return nil`
for Harmony control flow)
- prevent execution of the original method (and other harmony
patches), independently of modifying the return value
