edit predictions: Disable "This Buffer" option when disabled for language (#25566)

![image](https://github.com/user-attachments/assets/7b888c7d-a1e9-4d0b-ba6d-9a41916acf79)


Release Notes:

- edit prediction: Disable "This Buffer" option when predictions are
disabled for its language

crates/ui/src/components/context_menu.rs

@@ -95,8 +95,8 @@ impl ContextMenuEntry {
         self
     }
 
-    pub fn action(mut self, action: Option<Box<dyn Action>>) -> Self {
-        self.action = action;
+    pub fn action(mut self, action: Box<dyn Action>) -> Self {
+        self.action = Some(action);
         self
     }