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/ui/src/components/icon.rs

@@ -117,6 +117,7 @@ pub enum IconName {
     Dash,
     Delete,
     Disconnected,
+    Download,
     Ellipsis,
     Envelope,
     Escape,
@@ -248,6 +249,7 @@ impl IconName {
             IconName::Dash => "icons/dash.svg",
             IconName::Delete => "icons/delete.svg",
             IconName::Disconnected => "icons/disconnected.svg",
+            IconName::Download => "icons/download.svg",
             IconName::Ellipsis => "icons/ellipsis.svg",
             IconName::Envelope => "icons/feedback.svg",
             IconName::Escape => "icons/escape.svg",