Add copilot crate

Refactor HTTP and github release downloading into util
Lazily download / upgrade the copilot LSP from Zed

Co-authored-by: Max <max@zed.dev>
Co-Authored-By: Antonio <antonio@zed.dev>

crates/util/src/http.rs

@@ -0,0 +1,117 @@
+pub use anyhow::{anyhow, Result};
+use futures::future::BoxFuture;
+use isahc::config::{Configurable, RedirectPolicy};
+pub use isahc::{
+    http::{Method, Uri},
+    Error,
+};
+pub use isahc::{AsyncBody, Request, Response};
+use smol::future::FutureExt;
+#[cfg(feature = "test-support")]
+use std::fmt;
+use std::{sync::Arc, time::Duration};
+pub use url::Url;
+
+pub trait HttpClient: Send + Sync {
+    fn send(&self, req: Request<AsyncBody>) -> BoxFuture<Result<Response<AsyncBody>, Error>>;
+
+    fn get<'a>(
+        &'a self,
+        uri: &str,
+        body: AsyncBody,
+        follow_redirects: bool,
+    ) -> BoxFuture<'a, Result<Response<AsyncBody>, Error>> {
+        let request = isahc::Request::builder()
+            .redirect_policy(if follow_redirects {
+                RedirectPolicy::Follow
+            } else {
+                RedirectPolicy::None
+            })
+            .method(Method::GET)
+            .uri(uri)
+            .body(body);
+        match request {
+            Ok(request) => self.send(request),
+            Err(error) => async move { Err(error.into()) }.boxed(),
+        }
+    }
+
+    fn post_json<'a>(
+        &'a self,
+        uri: &str,
+        body: AsyncBody,
+    ) -> BoxFuture<'a, Result<Response<AsyncBody>, Error>> {
+        let request = isahc::Request::builder()
+            .method(Method::POST)
+            .uri(uri)
+            .header("Content-Type", "application/json")
+            .body(body);
+        match request {
+            Ok(request) => self.send(request),
+            Err(error) => async move { Err(error.into()) }.boxed(),
+        }
+    }
+}
+
+pub fn client() -> Arc<dyn HttpClient> {
+    Arc::new(
+        isahc::HttpClient::builder()
+            .connect_timeout(Duration::from_secs(5))
+            .low_speed_timeout(100, Duration::from_secs(5))
+            .build()
+            .unwrap(),
+    )
+}
+
+impl HttpClient for isahc::HttpClient {
+    fn send(&self, req: Request<AsyncBody>) -> BoxFuture<Result<Response<AsyncBody>, Error>> {
+        Box::pin(async move { self.send_async(req).await })
+    }
+}
+
+#[cfg(feature = "test-support")]
+pub struct FakeHttpClient {
+    handler: Box<
+        dyn 'static
+            + Send
+            + Sync
+            + Fn(Request<AsyncBody>) -> BoxFuture<'static, Result<Response<AsyncBody>, Error>>,
+    >,
+}
+
+#[cfg(feature = "test-support")]
+impl FakeHttpClient {
+    pub fn create<Fut, F>(handler: F) -> Arc<dyn HttpClient>
+    where
+        Fut: 'static + Send + futures::Future<Output = Result<Response<AsyncBody>, Error>>,
+        F: 'static + Send + Sync + Fn(Request<AsyncBody>) -> Fut,
+    {
+        Arc::new(Self {
+            handler: Box::new(move |req| Box::pin(handler(req))),
+        })
+    }
+
+    pub fn with_404_response() -> Arc<dyn HttpClient> {
+        Self::create(|_| async move {
+            Ok(Response::builder()
+                .status(404)
+                .body(Default::default())
+                .unwrap())
+        })
+    }
+}
+
+#[cfg(feature = "test-support")]
+impl fmt::Debug for FakeHttpClient {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("FakeHttpClient").finish()
+    }
+}
+
+#[cfg(feature = "test-support")]
+impl HttpClient for FakeHttpClient {
+    fn send(&self, req: Request<AsyncBody>) -> BoxFuture<Result<Response<AsyncBody>, Error>> {
+        let future = (self.handler)(req);
+        Box::pin(async move { future.await.map(Into::into) })
+    }
+}