refactor(iroh-net)!: Rework relay-server binary, more configurable, r…

…everse-proxy support (n0-computer#2341)

## Description

This re-architects the relay-server binary. There is now a struct with
detailed configuration which runs the entire server and aborts the
server on drop. This simplifies running the server in various
situations, including tests. The configuration is now done using a
declarative struct, which supports more control over how it runs so it
can be more easily used behind a reverse proxy, without TLS etc.

This is aiming to fix n0-computer#2177, n0-computer#2179 and n0-computer#2178.

## Breaking Changes

The configuration file format has changed, deployments will need to
updated. For the full format see `struct Config` in
`iroh-net/src/bin/iroh-relay.rs`. Here a summary:

- The 3 parts of the server now have an independent enable setting:
`enable_relay`, `enable_stun` and `enable_metrics`. If omitted they
default to `true`.
- The way to specify which addresses the server listens on has changed:
`http_bind_addr` is for the relay server, `stun_bind_addr` for the STUN
server, `metrics_bind_addr` is for the optional metrics server and
`tls.https_bind_addr` is for when TLS is enabled. Note these are now all
full socket addresses. All have sensible defaults if omitted.
- There are new options in `tls.cert_path` and `tls.key_path` which
allow more control over where the manual TLS keys are to be read from.
- `iroh_net::defaults::DEFAULT_RELAY_STUN_PORT` has been renamed to
`iroh_net::defaults::DEFAULT_STUN_PORT`.

TBD: some APIs changed as well.  Why are they not all private?


## Notes & open questions

* The `iroh_net::relay::iroh_relay` crate name is a bit weird. But
`iroh_net::relay::server` is already taken. Maybe `iroh_net::relay::bin`
could work, but that would be weird when using it from code in other
places.
* The `ServerConfig` struct is a declarative way of controlling the new
server interface. It's kind of nice to use. Bu it is a public API that
will be a breaking change every time it changes, and it will change.
Maybe it's worth creating a builder API for this. But maybe that's
something to only tackle when it is a real demand. I feel like the
`iroh_net::relay::server` builders are an attempt at doing this earlier
than needed.

## Change checklist

- [x] Self-review.
- [x] Documentation updates if relevant.
- [x] Tests if relevant.
- [x] All breaking changes documented.

iroh-cli/src/commands/doctor.rs

@@ -27,7 +27,7 @@ use iroh::{
     },
     docs::{Capability, DocTicket},
     net::{
-        defaults::DEFAULT_RELAY_STUN_PORT,
+        defaults::DEFAULT_STUN_PORT,
         discovery::{
             dns::DnsDiscovery, pkarr_publish::PkarrPublisher, ConcurrentDiscovery, Discovery,
         },
@@ -93,7 +93,7 @@ pub enum Commands {
         #[clap(long)]
         stun_host: Option<String>,
         /// The port of the STUN server.
-        #[clap(long, default_value_t = DEFAULT_RELAY_STUN_PORT)]
+        #[clap(long, default_value_t = DEFAULT_STUN_PORT)]
         stun_port: u16,
     },
     /// Wait for incoming requests from iroh doctor connect
@@ -631,7 +631,7 @@ async fn passive_side(gui: Gui, connection: Connection) -> anyhow::Result<()> {
 }
 
 fn configure_local_relay_map() -> RelayMap {
-    let stun_port = DEFAULT_RELAY_STUN_PORT;
+    let stun_port = DEFAULT_STUN_PORT;
     let url = "http://localhost:3340".parse().unwrap();
     RelayMap::default_from_node(url, stun_port)
 }