desktop: switch workspaces and optionally raise in desktop_focus_view()

desktop: switch workspaces and optionally raise in desktop_focus_view()

Make desktop_focus_view() always switch to the workspace containing the
view being focused. It doesn't make much sense for an invisible view to
have the keyboard focus.

Also add an optional "raise" parameter to desktop_focus_view(). This
allows the common pattern of desktop_focus_view() + view_move_to_front()
to be reduced to a single function call.