feat: expanding the functionality of utils.sh and combining logic

Adding more functionality to the utils scripts in order to then reduce
the amount of duplication in task scripts within build-definitions
including:
* Parsing pullspecs
* Getting pullspecs in various forms of digest and tag
* Getting the base image
* Getting a matching FBC catalog image
* Rendering a catalog and reusing the cached output

Combining logic for extracting unique differential properties between a
FBC fragment and its matching catalog image
* Extracting unique bundles from the catalog
* Extracting related images from the catalog

fixes #353

Signed-off-by: arewm <[email protected]>