Add SystemClock (#8239)

This PR adds a `SystemClock` trait for abstracting away the system
clock.

This allows us to swap out the real system clock with a
`FakeSystemClock` in the tests, thus allowing the fake passage of time.

We're using this in `Telemetry` to better mock the clock for testing
purposes.

Release Notes:

- N/A

crates/workspace/Cargo.toml

@@ -25,6 +25,7 @@ async-recursion = "1.0.0"
 bincode = "1.2.1"
 call.workspace = true
 client.workspace = true
+clock.workspace = true
 collections.workspace = true
 db.workspace = true
 derive_more.workspace = true

crates/workspace/src/workspace.rs

@@ -397,8 +397,9 @@ impl AppState {
 
         let fs = fs::FakeFs::new(cx.background_executor().clone());
         let languages = Arc::new(LanguageRegistry::test());
+        let clock = Arc::new(clock::FakeSystemClock::default());
         let http_client = util::http::FakeHttpClient::with_404_response();
-        let client = Client::new(http_client.clone(), cx);
+        let client = Client::new(clock, http_client.clone(), cx);
         let user_store = cx.new_model(|cx| UserStore::new(client.clone(), cx));
         let workspace_store = cx.new_model(|cx| WorkspaceStore::new(client.clone(), cx));