Use Tokio::spawn instead of getting an executor handle (#36701)

This was causing panics due to the handles being dropped out of order.
It doesn't seem possible to guarantee the correct drop ordering given
that we're holding them over await points, so lets just spawn on the
tokio executor itself which gives us access to the state we needed those
handles for in the first place.

Fixes: ZED-1R

Release Notes:

- N/A

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>
Co-authored-by: Marshall Bowers <git@maxdeviant.com>

crates/client/src/client.rs

@@ -1290,19 +1290,21 @@ impl Client {
                 "http" => Http,
                 _ => Err(anyhow!("invalid rpc url: {}", rpc_url))?,
             };
-            let rpc_host = rpc_url
-                .host_str()
-                .zip(rpc_url.port_or_known_default())
-                .context("missing host in rpc url")?;
 
-            let stream = {
-                let handle = cx.update(|cx| gpui_tokio::Tokio::handle(cx)).ok().unwrap();
-                let _guard = handle.enter();
-                match proxy {
-                    Some(proxy) => connect_proxy_stream(&proxy, rpc_host).await?,
-                    None => Box::new(TcpStream::connect(rpc_host).await?),
+            let stream = gpui_tokio::Tokio::spawn_result(cx, {
+                let rpc_url = rpc_url.clone();
+                async move {
+                    let rpc_host = rpc_url
+                        .host_str()
+                        .zip(rpc_url.port_or_known_default())
+                        .context("missing host in rpc url")?;
+                    Ok(match proxy {
+                        Some(proxy) => connect_proxy_stream(&proxy, rpc_host).await?,
+                        None => Box::new(TcpStream::connect(rpc_host).await?),
+                    })
                 }
-            };
+            })?
+            .await?;
 
             log::info!("connected to rpc endpoint {}", rpc_url);