dotnet: WIP PR for trying to fix AOT codegen

[alebcay]

• Have you followed the guidelines for contributing?
• Have you ensured that your commits follow the commit style guide?
• Have you checked that there aren't other open pull requests for the same formula update/change?
• Have you built your formula locally with HOMEBREW_NO_INSTALL_FROM_API=1 brew install --build-from-source <formula>, where <formula> is the name of the formula you're submitting?
• Is your test running fine brew test <formula>, where <formula> is the name of the formula you're submitting?
• Does your build pass brew audit --strict <formula> (after doing HOMEBREW_NO_INSTALL_FROM_API=1 brew install --build-from-source <formula>)? If this is a new formula, does it pass brew audit --new <formula>?

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• Confirm that current build process results in build/publish failure by adding steps in test (control case).
• Try setting /p:PortableBuild=true as a fix. If build and modified test succeeds, download the resulting bottles and see how linkage differs.
• Try setting /p:BundleNativeAotCompiler=false as a fix. If build and modified test succeeds, confirm no change in linkage and that the test is indeed pulling AOT compiler from NuGet.