[wasm] Use source generator for results data json serialization (#89177)

[wasm] Use source generator for results data json serialization (#89177)

This fixes problem with posting results, where we crashed with:

    MONO_WASM:    at System.Text.Json.ThrowHelper.ThrowInvalidOperationException_JsonSerializerOptionsNoTypeInfoResolverSpecified()
       at System.Text.Json.JsonSerializerOptions.MakeReadOnly()
       at System.Text.Json.JsonSerializerOptions.ConfigureForJsonSerializer()
       at System.Text.Json.JsonSerializer.GetTypeInfo(JsonSerializerOptions , Type )
       at System.Text.Json.JsonSerializer.GetTypeInfo[JsonResultsData](JsonSerializerOptions )
       at System.Text.Json.JsonSerializer.Serialize[JsonResultsData](JsonResultsData , JsonSerializerOptions )
       at Sample.Test.GetJsonResults()
       at Sample.Test.GetFullJsonResults()
       at Sample.Test.__Wrapper_GetFullJsonResults_234275758(JSMarshalerArgument* __arguments_buffer)
    ManagedError@http://localhost:8781/_framework/dotnet.runtime.js:3:29628
    vr@http://localhost:8781/_framework/dotnet.runtime.js:3:34757
    Ao@http://localhost:8781/_framework/dotnet.runtime.js:3:52015
    To/U</<@http://localhost:8781/_framework/dotnet.runtime.js:3:50790
    init@http://localhost:8781/main.js:118:19
    setTimeout handler*yieldBench/<@http://localhost:8781/main.js:129:49
    yieldBench@http://localhost:8781/main.js:129:16
    init@http://localhost:8781/main.js:108:45
    setTimeout handler*yieldBench/<@http://localhost:8781/main.js:129:49
    yieldBench@http://localhost:8781/main.js:129:16
    init@http://localhost:8781/main.js:108:45