Pass through all repos to the initalizeManifest() function. Each
pipeline will then select which repositories it needs based on the
PackageSets field of each repository.
Before, we only passed global repos down to the manifest generators and
pipeline-specific repositories would only be used if they were attached
to package sets and were handled explicitly by a pipeline generator.
The repositories of the "blueprint" package set are explicitly added to
the workload and returned by the "os" pipeline.
The repositories of the "installer" package set are explicitly added to
the "anaconda-tree" pipeline.
If a repository was specified for any other pipeline, for example
"build", the repositories for the that package set were never added to
the pipeline.
Fixes#3290
2a4cd1966d