More extensibility friendly DefaultHttpMessageInvokerFactory

[ArturDorochowicz]

I'd like to suggest extracting the handler creation here to a separate virtual method:

BFF/src/Duende.Bff.Yarp/DefaultHttpMessageInvokerFactory.cs

Lines 26 to 32 in 0ad3cde

	var socketsHandler = new SocketsHttpHandler
	{
	UseProxy = false,
	AllowAutoRedirect = false,
	AutomaticDecompression = DecompressionMethods.None,
	UseCookies = false
	};

Something like:

protected virtual HttpMessageHandler CreateHandler(string localPath)
{
   return new SocketsHttpHandler { /* ... */ };
}

This will allow derived classes to wrap the base handler in additional DelegatingHandler(s). For instance:

protected override HttpMessageHandler CreateHandler(string localPath) 
{
   var handler = base.CreateHandler(localPath);
   var wrapper = new MyDelegatingHandler { InnerHandler = handler };
   return wrapper;
}

Currently if we just want to wrap the handler, we have to copy the code creating the SocketsHttpHandler from DefaultHttpMessageInvokerFactory.CreateClient.

[leastprivilege]

Sounds reasonable, do you want to propose a PR?