Introduce a separate backend service for LLM calls (#15831)

This PR introduces a separate backend service for making LLM calls.

It exposes an HTTP interface that can be called by Zed clients. To call
these endpoints, the client must provide a `Bearer` token. These tokens
are issued/refreshed by the collab service over RPC.

We're adding this in a backwards-compatible way. Right now the access
tokens can only be minted for Zed staff, and calling this separate LLM
service is behind the `llm-service` feature flag (which is not
automatically enabled for Zed staff).

Release Notes:

- N/A

---------

Co-authored-by: Marshall <marshall@zed.dev>
Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>

crates/collab/src/api/billing.rs

@@ -120,7 +120,7 @@ async fn create_billing_subscription(
         .zip(app.config.stripe_price_id.clone())
     else {
         log::error!("failed to retrieve Stripe client or price ID");
-        Err(Error::Http(
+        Err(Error::http(
             StatusCode::NOT_IMPLEMENTED,
             "not supported".into(),
         ))?
@@ -201,7 +201,7 @@ async fn manage_billing_subscription(
 
     let Some(stripe_client) = app.stripe_client.clone() else {
         log::error!("failed to retrieve Stripe client");
-        Err(Error::Http(
+        Err(Error::http(
             StatusCode::NOT_IMPLEMENTED,
             "not supported".into(),
         ))?

crates/collab/src/api/events.rs

@@ -206,14 +206,14 @@ pub async fn post_hang(
     body: Bytes,
 ) -> Result<()> {
     let Some(expected) = calculate_json_checksum(app.clone(), &body) else {
-        return Err(Error::Http(
+        return Err(Error::http(
             StatusCode::INTERNAL_SERVER_ERROR,
             "events not enabled".into(),
         ))?;
     };
 
     if checksum != expected {
-        return Err(Error::Http(
+        return Err(Error::http(
             StatusCode::BAD_REQUEST,
             "invalid checksum".into(),
         ))?;
@@ -265,25 +265,25 @@ pub async fn post_panic(
     body: Bytes,
 ) -> Result<()> {
     let Some(expected) = calculate_json_checksum(app.clone(), &body) else {
-        return Err(Error::Http(
+        return Err(Error::http(
             StatusCode::INTERNAL_SERVER_ERROR,
             "events not enabled".into(),
         ))?;
     };
 
     if checksum != expected {
-        return Err(Error::Http(
+        return Err(Error::http(
             StatusCode::BAD_REQUEST,
             "invalid checksum".into(),
         ))?;
     }
 
     let report: telemetry_events::PanicRequest = serde_json::from_slice(&body)
-        .map_err(|_| Error::Http(StatusCode::BAD_REQUEST, "invalid json".into()))?;
+        .map_err(|_| Error::http(StatusCode::BAD_REQUEST, "invalid json".into()))?;
     let panic = report.panic;
 
     if panic.os_name == "Linux" && panic.os_version == Some("1.0.0".to_string()) {
-        return Err(Error::Http(
+        return Err(Error::http(
             StatusCode::BAD_REQUEST,
             "invalid os version".into(),
         ))?;
@@ -362,14 +362,14 @@ pub async fn post_events(
     body: Bytes,
 ) -> Result<()> {
     let Some(clickhouse_client) = app.clickhouse_client.clone() else {
-        Err(Error::Http(
+        Err(Error::http(
             StatusCode::NOT_IMPLEMENTED,
             "not supported".into(),
         ))?
     };
 
     let Some(expected) = calculate_json_checksum(app.clone(), &body) else {
-        return Err(Error::Http(
+        return Err(Error::http(
             StatusCode::INTERNAL_SERVER_ERROR,
             "events not enabled".into(),
         ))?;
@@ -385,7 +385,7 @@ pub async fn post_events(
 
     let mut to_upload = ToUpload::default();
     let Some(last_event) = request_body.events.last() else {
-        return Err(Error::Http(StatusCode::BAD_REQUEST, "no events".into()))?;
+        return Err(Error::http(StatusCode::BAD_REQUEST, "no events".into()))?;
     };
     let country_code = country_code_header.map(|h| h.to_string());
 

crates/collab/src/api/extensions.rs

@@ -185,7 +185,7 @@ async fn download_extension(
         .clone()
         .zip(app.config.blob_store_bucket.clone())
     else {
-        Err(Error::Http(
+        Err(Error::http(
             StatusCode::NOT_IMPLEMENTED,
             "not supported".into(),
         ))?
@@ -202,7 +202,7 @@ async fn download_extension(
         .await?;
 
     if !version_exists {
-        Err(Error::Http(
+        Err(Error::http(
             StatusCode::NOT_FOUND,
             "unknown extension version".into(),
         ))?;