Add minimal proxy capabilities to dioxus serve

This adds an MVP of some proxying capabilities to the `dioxus serve`
server. The config is similar to that of `trunk serve`: the user can
specify one or more proxy backends under `[[web.proxy]]` in Dioxus.toml,
and the server will intercept requests targeted at the _path_ of that
configured backend and forward them to the backend server.

Example
-------

For example, if the dev server is serving on port 8080 with this config:

```
[[web.proxy]]
backend = "http://localhost:9000/api"
```

then requests to http://localhost:8080/api,
http://localhost:8080/api/ and http://localhost:8080/api/any-subpath
to be forwarded to the respective paths on http://localhost:9000.

This PR doesn't handle path rewriting or anything yet but it would be
fairly simple to add in future if anyone needs it.

Cargo.toml

@@ -36,6 +36,7 @@ regex = "1.5.4"
 chrono = "0.4.19"
 anyhow = "1.0.53"
 hyper = "0.14.17"
+hyper-rustls = "0.23.2"
 indicatif = "0.17.0-rc.11"
 subprocess = "0.2.9"