[mono][aot] Preserve P/Invoked symbols when stripping

[kotlarmilos]

Enable Mono AOT compiler to generate a list of symbols which get P/Invoked, so they can get preserved during stripping phase, instead of relying on a custom linker steps in Xamarin or stripping non-global symbols in MonoAOTCompiler msbuild task.

#79721 could be extended to output the list of P/Invoked symbols and possibly strip more from the final binary.

[marek-safar]

It'd also help us to check this feature does not regress

[ivanpovazan]

It seems WasmAppBuilder is doing something really similar (if not exactly what we need): https://github.com/dotnet/runtime/blob/main/src/tasks/WasmAppBuilder/PInvokeTableGenerator.cs
the feature also includes tests here: https://github.com/dotnet/runtime/blob/main/src/mono/wasm/Wasm.Build.Tests/PInvokeTableGeneratorTests.cs

PS although it does load assemblies (once again) which can negatively impact the build time.

[kotlarmilos]

SOD difference for HelloiOS binary when non-global symbols are stripped vs. only P/Invokes are preserved - #81361 (comment).