[ILLink] TrimMode=full is trimming UnmanagedCallersOnly in the final app

[pavelsavara]

To reproduce

• build runtime for WASI target
• ./dotnet.cmd build /p:TargetOS=wasi /p:TargetArchitecture=wasm /p:Configuration=Debug /t:RunSample .\src\mono\sample\wasi\native\ /p:TrimMode=full
• note I will apply workaround to the sample soon

Actual result
undefined symbol: ManagedFunc

Expected
ManagedFunc returned 42

Workaround
Use ilink descriptor

    <type fullname="Sample.Test">
        <method signature="System.Int32 MyExport(System.Int32)" />
    </type>

[dotnet-policy-service]

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[sbomer]

Duplicate of #101434