Allow keys to close a "hold"-ing window/pane after process exited

[bew]

Is your feature request related to a problem? Please describe.
When exit_behavior is set to hold, when a process exits it's pretty annoying to have to use the mouse (or extra keybindings) to close the window/pane.

Describe the solution you'd like
Allow the Enter or Ctrl-j key on the [Process completed] message to close the window/pane.

Taking inspiration from MobaXTerm, we could also have additional keybindings like r to restart the closed process (with the same params).

Describe alternatives you've considered
Mouse or additional keybindings to close the window/pane.