Allow AI interactions to be proxied through Zed's server so you don't need an API key (#7367)

Co-authored-by: Antonio <antonio@zed.dev>

Resurrected this from some assistant work I did in Spring of 2023.
- [x] Resurrect streaming responses
- [x] Use streaming responses to enable AI via Zed's servers by default
(but preserve API key option for now)
- [x] Simplify protobuf
- [x] Proxy to OpenAI on zed.dev
- [x] Proxy to Gemini on zed.dev
- [x] Improve UX for switching between openAI and google models
- We current disallow cycling when setting a custom model, but we need a
better solution to keep OpenAI models available while testing the google
ones
- [x] Show remaining tokens correctly for Google models
- [x] Remove semantic index
- [x] Delete `ai` crate
- [x] Cloud front so we can ban abuse
- [x] Rate-limiting
- [x] Fix panic when using inline assistant
- [x] Double check the upgraded `AssistantSettings` are
backwards-compatible
- [x] Add hosted LLM interaction behind a `language-models` feature
flag.

Release Notes:

- We are temporarily removing the semantic index in order to redesign it
from scratch.

---------

Co-authored-by: Antonio <antonio@zed.dev>
Co-authored-by: Antonio Scandurra <me@as-cii.com>
Co-authored-by: Thorsten <thorsten@zed.dev>
Co-authored-by: Max <max@zed.dev>

crates/collab/src/tests/test_server.rs

@@ -2,7 +2,7 @@ use crate::{
     db::{tests::TestDb, NewUserParams, UserId},
     executor::Executor,
     rpc::{Server, ZedVersion, CLEANUP_TIMEOUT, RECONNECT_TIMEOUT},
-    AppState, Config,
+    AppState, Config, RateLimiter,
 };
 use anyhow::anyhow;
 use call::ActiveCall;
@@ -93,17 +93,14 @@ impl TestServer {
             deterministic.clone(),
         )
         .unwrap();
-        let app_state = Self::build_app_state(&test_db, &live_kit_server).await;
+        let executor = Executor::Deterministic(deterministic.clone());
+        let app_state = Self::build_app_state(&test_db, &live_kit_server, executor.clone()).await;
         let epoch = app_state
             .db
             .create_server(&app_state.config.zed_environment)
             .await
             .unwrap();
-        let server = Server::new(
-            epoch,
-            app_state.clone(),
-            Executor::Deterministic(deterministic.clone()),
-        );
+        let server = Server::new(epoch, app_state.clone());
         server.start().await.unwrap();
         // Advance clock to ensure the server's cleanup task is finished.
         deterministic.advance_clock(CLEANUP_TIMEOUT);
@@ -482,12 +479,15 @@ impl TestServer {
 
     pub async fn build_app_state(
         test_db: &TestDb,
-        fake_server: &live_kit_client::TestServer,
+        live_kit_test_server: &live_kit_client::TestServer,
+        executor: Executor,
     ) -> Arc<AppState> {
         Arc::new(AppState {
             db: test_db.db().clone(),
-            live_kit_client: Some(Arc::new(fake_server.create_api_client())),
+            live_kit_client: Some(Arc::new(live_kit_test_server.create_api_client())),
             blob_store_client: None,
+            rate_limiter: Arc::new(RateLimiter::new(test_db.db().clone())),
+            executor,
             clickhouse_client: None,
             config: Config {
                 http_port: 0,
@@ -506,6 +506,8 @@ impl TestServer {
                 blob_store_access_key: None,
                 blob_store_secret_key: None,
                 blob_store_bucket: None,
+                openai_api_key: None,
+                google_ai_api_key: None,
                 clickhouse_url: None,
                 clickhouse_user: None,
                 clickhouse_password: None,