Allow canceling in-progress language server work (e.g. cargo check) (#13173)

Release Notes:

- Added a more detailed message in place of the generic `checking...`
messages when Rust-analyzer is running.
- Added a rate limit for language server status messages, to reduce
noisiness of those updates.
- Added a `cancel language server work` action which will cancel
long-running language server tasks.

---------

Co-authored-by: Richard <richard@zed.dev>

crates/lsp/src/lsp.rs

@@ -1351,6 +1351,14 @@ impl FakeLanguageServer {
 
     /// Simulate that the server has started work and notifies about its progress with the specified token.
     pub async fn start_progress(&self, token: impl Into<String>) {
+        self.start_progress_with(token, Default::default()).await
+    }
+
+    pub async fn start_progress_with(
+        &self,
+        token: impl Into<String>,
+        progress: WorkDoneProgressBegin,
+    ) {
         let token = token.into();
         self.request::<request::WorkDoneProgressCreate>(WorkDoneProgressCreateParams {
             token: NumberOrString::String(token.clone()),
@@ -1359,7 +1367,7 @@ impl FakeLanguageServer {
         .unwrap();
         self.notify::<notification::Progress>(ProgressParams {
             token: NumberOrString::String(token),
-            value: ProgressParamsValue::WorkDone(WorkDoneProgress::Begin(Default::default())),
+            value: ProgressParamsValue::WorkDone(WorkDoneProgress::Begin(progress)),
         });
     }