Serve guest-profiler results from a local web server

[jameysharp]

This is a proof of concept for #7666, but needs quite a bit of polish before merging.

[jameysharp]

If anyone has suggestions on how to do this better I'd be interested to hear them. In particular, I'm not happy with how many crate dependencies I had to add to the Wasmtime CLI to make this work.

Currently this PR reflects just enough hacking together of pieces to prove that #7666 is possible, so I'm not looking for review on small details, just the big picture design questions.

[tschneidereit]

An alternative approach that shouldn't introduce any additional runtime dependencies would be to self-host this. I.e., to embed a wasi-http/proxy component that can load the profile from a pre-opened directory and serve it from the incoming-handler.

Such a component should be straightforward to run, and, after stripping, be quite small.