Show Delete shortcuts in project panel context menu (#12250)

Closes https://github.com/zed-industries/zed/issues/12234 by making both
default keymap and the menu `Delete` action declarations to have the
same `skip_prompt` value.
`Trash` action got more explicit `skip_prompt` declarations in this PR,
but those were the defaults already, so not changed.

Now, `Delete` action in the project panel will always show a prompt
before removing, both on the keystroke and menu item click.
To note, VSCode does skips prompt for the `Trash` action, so we might
want to change that too (later?), the PR does not alter it.

Release Notes:

- Shows Delete action binding keys in the project panel context menu
([12234](https://github.com/zed-industries/zed/issues/12234))