elm_code: make the hoversel not focusable.
Summary: Disabling focus prevents incorrect operations.
With EDI, use mouse (cut/copy/paste).
Due to the focus passing to the hoversel we break focus in the
application when it's lost. By disabling this cut/copy/paste
works as it should. A similar approach was used in elm_entry.
Reviewed By: ajwillia.ms
Differential Revision: https://phab.enlightenment.org/D6986