Introduce MagicOnion.Server.JsonTranscoding

[mayuki]

This PR introduces JSON transcoding support and Swagger integration.

These changes enhance the MagicOnion framework by adding support for JSON transcoding for Unary services and Swagger, making it easier to build and document gRPC services with JSON endpoints.

The feature inspired by Microsoft.AspNetCore.Grpc.JsonTranscoding.

This is the successor to the previous MagicOnion.Server.HttpGateway, but it is a completely new implementation and is not compatible, and is mainly intended for development support purposes.

• Remove MagicOnion.Server.HttpGateway #859

Warning

This feature is not intented for use in the Production environment.

If you want to provide Web-based (HTTP/1) APIs, we strongly recommend using ASP.NET Core Web API instead.

By default, JsonTranscoding cannot be enabled in the Production environment. You need to change MagicOnionJsonTranscodingOptions.AllowEnableInNonDevelopmentEnvironment to true.

var builder = WebApplication.CreateBuilder(args);

// Add MagicOnion services to the container and enable JSON transcoding feature.
builder.Services.AddMagicOnion().AddJsonTranscoding();
// Add MagicOnion JSON transcoding Swagger support.
builder.Services.AddMagicOnionJsonTranscodingSwagger();
// Add Swagger generator services.
builder.Services.AddSwaggerGen(options =>
{
    // Reflect the XML documentation comments of the service definition in Swagger.
    options.IncludeMagicOnionXmlComments(Path.Combine(AppContext.BaseDirectory, "JsonTranscodingSample.Shared.xml"));
});

var app = builder.Build();

// Configure the HTTP request pipeline.

// Enable middleware to serve generated Swagger as a JSON endpoint.
app.UseSwagger();
if (app.Environment.IsDevelopment())
{
    app.UseSwaggerUI(c =>
    {
        c.SwaggerEndpoint("/swagger/v1/swagger.json", "My API V1");
    });
}

app.MapMagicOnionService();
app.MapGet("/", () => "Communication with gRPC endpoints must be made through a gRPC client. To learn how to create a client, visit: https://go.microsoft.com/fwlink/?linkid=2086909");

app.Run();