Add keyboard shortcut to suppress prompt while deleting files/dirs (#9452)

Completes #7228.
Adds back Backspace as the main delete key binding and makes Linux
bindings consistent with macOS

Release Notes:
- ⌘-Delete/⌘-Backspace will now suppress deletion confirmation prompts
in project panel
([#7228](https://github.com/zed-industries/zed/issues/7228)).

docs/src/configuring_zed__key_bindings.md

@@ -378,6 +378,7 @@ But, it was impossible to take into account the `{` and `}` when he was typing s
 | Copy relative path      | Project Panel | `Alt` + `⌘` + `Shift` + `C` |
 | Cut                     | Project Panel | `⌘` + `X`                   |
 | Delete                  | Project Panel | `Backspace`                 |
+| Delete (no prompt)      | Project Panel | `⌘` + `Backspace`           |
 | Expand selected entry   | Project Panel | `Right`                     |
 | New directory           | Project Panel | `Alt` + `⌘` + `N`           |
 | New file                | Project Panel | `Command + N`               |