Show file open error view instead of the modal (#36764)

Closes https://github.com/zed-industries/zed/issues/36672

Before:
either 
<img width="966" height="642" alt="image"
src="https://github.com/user-attachments/assets/7263ea3c-3d48-4f4d-be9e-16b24ca6f60b"
/>
(when opening from the project panel)

or

<img width="959" height="1019" alt="image"
src="https://github.com/user-attachments/assets/834041d4-f4d6-46db-b333-803169ec4803"
/>

(for the rest of the cases)

After:

<img width="2032" height="1167" alt="Screenshot 2025-08-22 at 19 34 10"
src="https://github.com/user-attachments/assets/1aa4530b-69f6-4c3a-8ea1-d4035dbb28da"
/>

(the unified error view)

Release Notes:

- Improved unsupported file opening in Zed

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/zed_actions/src/lib.rs

@@ -156,7 +156,10 @@ pub mod workspace {
             #[action(deprecated_aliases = ["editor::CopyPath", "outline_panel::CopyPath", "project_panel::CopyPath"])]
             CopyPath,
             #[action(deprecated_aliases = ["editor::CopyRelativePath", "outline_panel::CopyRelativePath", "project_panel::CopyRelativePath"])]
-            CopyRelativePath
+            CopyRelativePath,
+            /// Opens the selected file with the system's default application.
+            #[action(deprecated_aliases = ["project_panel::OpenWithSystem"])]
+            OpenWithSystem,
         ]
     );
 }