[browser] Migrate runtime tests to WebAssembly SDK

[maraf]

• We need to produce a newest possible Wasm SDK pack from runtime build
• The SDK that is being used to build runtime is older
• If there is an incompatible change, we will duplicate the Microsoft.NET.Sdk.WebAssembly.Pack in the sources for a limited period and use the one compatible with runtime's .NET SDK for running tests, and publish the other one for public builds

[dotnet-policy-service]

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