Fix null-coalescing and null-conditional operator usage with UnityEngine.Object

https://blogs.unity3d.com/2014/05/16/custom-operator-should-we-keep-it/

https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/null-coalescing-operator
https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/null-conditional-operators

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IL to match is pretty much just some form of value/field **load** followed by a `brtrue`/`brtrue.s`. The latter just needs to be replaced with a call to `[UnityEngine.CoreModule]UnityEngine.Object::op_Inequality(class [UnityEngine.CoreModule]UnityEngine.Object, class [UnityEngine.CoreModule]UnityEngine.Object)` and a `brfalse`/`brfalse.s` afterwards.
Only do this when the loaded value/field is inheriting from `UnityEngine.Object` of course.