Il2cpp stability

[HookedBehemoth]

Thank you for all the work on this tool.
I've tried to use this on an il2cpp game which obfuscates some of it's networking functionality and found that it caused a lot of spam when inspecting any items.
These patches helped working around my issues but I've not tested against all targets that can be built.

I'm happy to make any alterations to get this code merged.

I've found that the GUILayoutOption constructor and GetLastRect got stripped so I've implemented shims that accomplish the same on IL2CPP, while calling the original on mono.
I've choosen to leave the changes made in the feature initializer so that similar issues don't cause a fatal and only the affected component fails.
SceneManager seems to be in another assembly and since our Il2Cpp interop assemblies can't use fields, the onPreRender/onPostRender search failed.
The ObfuscatedNameAttribute is added by the unhollower and using these names when they exist solved most of the remaining issues.
2429694 & 11bdf73 fix issues that should be present on all targets.

While working on this I've also implemented additional scene filters though the implementation isn't pretty.

[ManlyMarco]

Looks good to me, thanks for the PR!

I'm not sure how much the shims will help, the IL2CPP games that I've tried were missing a lot more methods to the point where it might be necessary to rewrite parts of the IMGUI dll and just directly call the externs from it. If this is enough for the games that you've tried then that's great though!