[mono][Browser] Interpreter doesn't fully support UnmanagedCallersOnly

[EgorBo]

Currently, the only way to pass a managed callback to a pinvoke in Mono-Wasm-Interp is to use IntPtr + Marshal.GetFunctionPointerForDelegate + MonoPinvokeCallbackAttribute.

/cc @vargaz

I will use link to this issue for workarounds.

Tagging subscribers to this area: @BrzVlad, @lewurm
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[EgorBo]

Once fixed, MonoPInvokeCallbackAttribute should be removed from System.Private.CoreLib

[jkotas]

I have extended this workaround to apply to all Mono targets in #39082