Add explicit `force_yes` arg for non-explicit downgrades

User was using a pin file to define a non-standard repo which may have a
lower version.  Version was not explicitly defined, so the state was not
detecting a downgrade.  Add ability to pass in --force-yes (with
warnings that it could be dangerous).
Merge pull request #8714 from basepi/aptforceyes

Add explicit `force_yes` arg for non-explicit downgrades