[http-client-csharp] http/parameters/spread cannot build

[ArcturusZhang]

I am not sure why this previous could pass, but now I found it cannot compile.

        /// <summary>
        /// [Protocol Method] spreadParameterWithInnerModel
        /// <list type="bullet">
        /// <item>
        /// <description> This <see href="https://aka.ms/azsdk/net/protocol-methods">protocol method</see> allows explicit creation of the request and processing of the response for advanced scenarios. </description>
        /// </item>
        /// </list>
        /// </summary>
        /// <param name="id"></param>
        /// <param name="x-ms-test-header"></param>
        /// <param name="content"> The content to send as the body of the request. </param>
        /// <param name="options"> The request options, which can override default behaviors of the client pipeline on a per-call basis. </param>
        /// <exception cref="ArgumentNullException"> <paramref name="id"/>, <paramref name="x-ms-test-header"/> or <paramref name="content"/> is null. </exception>
        /// <exception cref="ClientResultException"> Service returned a non-success status code. </exception>
        /// <returns> The response returned from the service. </returns>
        public virtual ClientResult SpreadParameterWithInnerModel(string id, string xMsTestHeader, BinaryContent content, RequestOptions options = null)

The xml doc for x-ms-test-header is incorrect - the parameter's name is xMsTestHeader.

How to reproduce:

1. cd into ./packages/http-client-csharp directory
2. Run script ./eng/scripts/Generate.ps1 parameters/spread -Stubbed $false
3. Run dotnet build .\generator\TestProjects\CadlRanch\http\parameters\spread\Parameters.Spread.sln and you would see this cannot build.