dim: abstract -i interactive pause to a function

Fixes shellcheck SC2089: Quotes/backslashes will be treated
literally. Use an array.

Fixes shellcheck SC2090: Quotes/backslashes in this variable will not be
respected.

Acked-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>