[Helm integration] Follow up to #846 - change unpacking to direct image registry client approach

[bentito]

PR #846 allows operator-controller to use helm under the hood for package installs. It is using a separate binary, unpack, to manage image unpacking. This issue proposes to use a direct image registry client approach to save the need to create a separate binary. The work would be very similar to that done on rukpak here: https://github.com/operator-framework/rukpak/pull/874