Rename the OpenFile action to OpenSelectedFilename to better reflect its function (#22494)

Release Notes:

- Renamed the `OpenFile` action to `OpenSelectedFilename` for clarity

crates/editor/src/editor.rs

@@ -9503,7 +9503,7 @@ impl Editor {
         url_finder.detach();
     }
 
-    pub fn open_file(&mut self, _: &OpenFile, cx: &mut ViewContext<Self>) {
+    pub fn open_selected_filename(&mut self, _: &OpenSelectedFilename, cx: &mut ViewContext<Self>) {
         let Some(workspace) = self.workspace() else {
             return;
         };