Remove all the internal package that are now in the
github.com/osbuild/images package and vendor it.
A new function in internal/blueprint/ converts from an osbuild-composer
blueprint to an images blueprint. This is necessary for keeping the
blueprint implementation in both packages. In the future, the images
package will change the blueprint (and most likely rename it) and it
will only be part of the osbuild-composer internals and interface. The
Convert() function will be responsible for converting the blueprint into
the new configuration object.
This adds a function, CleanupOldCacheDirs, that checks the dirs under
/var/cache/osbuild-composer/rpmmd/ and removes files and directories
that don't match the current list of supported distros.
This will clean up the cache from old releases as the are retired, and
will also cleanup the old top level cache directory structure after an
upgrade.
NOTE: This function does not return errors, any real problems it
encounters will also be caught by the cache initialization code and
handled there.
