rust: use native-tls for the build-time CLI download (#1964)

build/in_process.rs and build/out_of_process.rs download the Copilot CLI with
ureq, which was on the rustls (tls) feature and pulled rustls and ring into the
build. Switch ureq to native-tls and build the connector in both download paths
so the build no longer compiles rustls/ring (schannel on Windows,
Security.framework on macOS, OpenSSL on Linux).

Co-authored-by: Shivam Chawla <13963817+Shivam60@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Shivam60

rust/Cargo.lock

@@ -97,5 +97,6 @@ flate2 = "1"
 serde_json = "1"
 sha2 = "0.10"
 tar = "0.4"
-ureq = { version = "2", default-features = false, features = ["tls"] }
+ureq = { version = "2", default-features = false, features = ["native-tls"] }
+native-tls = "0.2"
 zip = { version = "2", default-features = false, features = ["deflate"] }

rust/Cargo.toml

@@ -631,7 +631,12 @@ struct DownloadError {
 }
 
 fn try_download(url: &str) -> Result<Vec<u8>, DownloadError> {
+    let connector = native_tls::TlsConnector::new().map_err(|e| DownloadError {
+        message: format!("native-tls init error: {e}"),
+        transient: false,
+    })?;
     let agent = ureq::AgentBuilder::new()
+        .tls_connector(std::sync::Arc::new(connector))
         .timeout_connect(Duration::from_secs(30))
         .timeout_read(Duration::from_secs(120))
         .build();

rust/build/in_process.rs

@@ -599,7 +599,12 @@ struct DownloadError {
 }
 
 fn try_download(url: &str) -> Result<Vec<u8>, DownloadError> {
+    let connector = native_tls::TlsConnector::new().map_err(|e| DownloadError {
+        message: format!("native-tls init error: {e}"),
+        transient: false,
+    })?;
     let agent = ureq::AgentBuilder::new()
+        .tls_connector(std::sync::Arc::new(connector))
         .timeout_connect(Duration::from_secs(30))
         .timeout_read(Duration::from_secs(120))
         .build();