Include display text for LSP commands in errors (#23012)

https://github.com/zed-industries/zed/pull/23011 adds display of errors
in the UI so it's now more important to contextualize these.

Release Notes:

- N/A

crates/project/src/lsp_ext_command.rs

@@ -47,6 +47,10 @@ impl LspCommand for ExpandMacro {
     type LspRequest = LspExpandMacro;
     type ProtoRequest = proto::LspExtExpandMacro;
 
+    fn display_name(&self) -> &str {
+        "Expand macro"
+    }
+
     fn to_lsp(
         &self,
         path: &Path,
@@ -171,6 +175,10 @@ impl LspCommand for OpenDocs {
     type LspRequest = LspOpenDocs;
     type ProtoRequest = proto::LspExtOpenDocs;
 
+    fn display_name(&self) -> &str {
+        "Open docs"
+    }
+
     fn to_lsp(
         &self,
         path: &Path,
@@ -284,6 +292,10 @@ impl LspCommand for SwitchSourceHeader {
     type LspRequest = LspSwitchSourceHeader;
     type ProtoRequest = proto::LspExtSwitchSourceHeader;
 
+    fn display_name(&self) -> &str {
+        "Switch source header"
+    }
+
     fn to_lsp(
         &self,
         path: &Path,