Run slash commands both on enter and on argument completion that requires it (#16283)

Release Notes:

- N/A

crates/project/src/project.rs

@@ -450,9 +450,10 @@ pub struct Completion {
     /// The raw completion provided by the language server.
     pub lsp_completion: lsp::CompletionItem,
     /// An optional callback to invoke when this completion is confirmed.
-    pub confirm: Option<Arc<dyn Send + Sync + Fn(CompletionIntent, &mut WindowContext)>>,
-    /// If true, the editor will show a new completion menu after this completion is confirmed.
-    pub show_new_completions_on_confirm: bool,
+    /// Returns, whether new completions should be retriggered after the current one.
+    /// If `true` is returned, the editor will show a new completion menu after this completion is confirmed.
+    /// if no confirmation is provided or `false` is returned, the completion will be committed.
+    pub confirm: Option<Arc<dyn Send + Sync + Fn(CompletionIntent, &mut WindowContext) -> bool>>,
 }
 
 impl std::fmt::Debug for Completion {
@@ -9128,7 +9129,6 @@ impl Project {
                         filter_range: Default::default(),
                     },
                     confirm: None,
-                    show_new_completions_on_confirm: false,
                 },
                 false,
                 cx,
@@ -10765,7 +10765,6 @@ async fn populate_labels_for_completions(
             documentation,
             lsp_completion,
             confirm: None,
-            show_new_completions_on_confirm: false,
         })
     }
 }