feat: Capture Native Instruction Addrs for Exceptions

[Swatinem]

For each of the chained Exceptions, this will query the list of native instruction addrs for the Exception from the libil2cpp runtime, to decorate the Sentry Event with those instruction addresses.

The libil2cpp APIs available to do this are completely internal, but have been there for a few releases and should not break in the near future.
One limitation is that the APIs return only addresses from, and relative to, the main GameAssembly library. As far as Unity is concerned, the game will only ever consist of a single Binary/Library and will not be split up into multiple things.

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[Swatinem]

I squashed all the commits, so this should be "ready to review", though there is still some work to do here.

Most notably:

• The runtime parts need to be conditionally compiled only on Unity >2020, and targeting il2cpp.
• There are some unrelated changes that @bitsandfoxes added I’m unsure about.

Especially the conditional compiler is something I need help with, as I have no idea how that would need to be done for Unity. Other than that, code is ready to review.

[bruno-garcia]

We still need a strategy to gracefully downgrade features depending on Unity versions. Will chat offline about it

[bruno-garcia]

This behavior just changed in the .NET SDK: https://github.com/getsentry/sentry-dotnet/pull/1672/files

We should instead refactor this out so we use either one strategy or the other, and have the base behavior on some base class or helper method

[Swatinem]

Thats a good point. I would have loved to just have an iterator that yields exceptions.
The .NET SDK could just map over that iterator to yield sentry exceptions. And this here could use the exact same iterator to zip.

[SimonCropp]

getsentry/sentry-dotnet#1733