Code mode for REPL that let's you run code against your mirage server.

[ryanto]

I'd like to use the repl to answer questions like...

• How do I serve binary responses with mirage?
• How do I serve streaming responses with mirage?

I can use the repl to show the mirage server, but the postman style UI is not the best at visualizing what the server is doing in these situations. I think adding a "code mode" would be helpful. Instead of using the postman UI it would allow you to write fetch requests that execute against the server.