Enable mono.wasm bindings in Blazor

[danroth27]

Moving to the mono.wasm bindings should enable support for WebSockets, HttpClient without addition code on our side, etc.

The work involved appears to be:

• Taking a mono build with the bindings turned on
• Adding a couple extra assemblies
• Removing our code where we set up our custom HttpClient handler
• Potentially change some of our JS-side code to change how Mono is started up.

[dazinator]

Is BrowserHttpMessageHandler no longer needed in latest preview bits then - i.e can you just use new HttpClient() or is there a replacement handler? Reason I ask is because in my Blazor client app (preview5) I am trying to configure my own HttpClient, and I can't find the type: BrowserHttpMessageHandler to pass to the constructor.

[danroth27]

@dazinator I believe we currently use some Mono magic to swap in our WebAssemblyHttpMessageHandler for Blazor apps. This issue tracks switching to use the built-in Mono handler as well as some other Mono provided bindings.