WIP: Using rust-nostr LocalRelay for testing

[f321x]

Some experimentation RE #23 with the rust-nostr nostr-relay-builder crate. But it seems like there are still problems as i constantly keep getting
[2024-10-03T22:59:22Z WARN nostr_relay_builder::local::internal] WebSocket protocol error: No "Connection: upgrade" header when trying to connect and connections close after a couple of seconds.
The relay is constructed from the default builder like this:

    let builder = RelayBuilder::default();
    let local_relay = LocalRelay::run(builder)
        .await
        .context("Failed to start local relay")?;

The nostr-relay-builder is explicitly stated as alpha version and the crates.io version is different from the repository, so its probably best to let it mature a bit first.