Switch from delete file by default to trash file by default (#10875)

TODO:

- [x] Don't immediately seg fault
- [x] Implement for directories 
- [x] Add cmd-delete to remove files
- [ ] ~~Add setting for trash vs. delete~~ You can just use keybindings
to change the behavior.

fixes https://github.com/zed-industries/zed/issues/7228
fixes https://github.com/zed-industries/zed/issues/5094

Release Notes:

- Added a new `project_panel::Trash` action and changed the default
behavior for `backspace` and `delete` in the project panel to send a
file to the systems trash, instead of permanently deleting it
([#7228](https://github.com/zed-industries/zed/issues/7228),
[#5094](https://github.com/zed-industries/zed/issues/5094)). The
original behavior can be restored by adding the following section to
your keybindings:

```json5
[
// ...Other keybindings...
  {
    "context": "ProjectPanel",
    "bindings": {
        "backspace": "project_panel::Delete",
        "delete": "project_panel::Delete",
    }
  }
]

assets/keymaps/default-linux.json

@@ -549,8 +549,8 @@
       "alt-ctrl-shift-c": "project_panel::CopyRelativePath",
       "f2": "project_panel::Rename",
       "enter": "project_panel::Rename",
-      "backspace": "project_panel::Delete",
-      "delete": "project_panel::Delete",
+      "backspace": "project_panel::Trash",
+      "delete": "project_panel::Trash",
       "ctrl-backspace": ["project_panel::Delete", { "skip_prompt": true }],
       "ctrl-delete": ["project_panel::Delete", { "skip_prompt": true }],
       "alt-ctrl-r": "project_panel::RevealInFinder",