fedora: Update versions in packages dict provided as loader argument

In a similar way to the debian lister, use the following versions in the
packages dictionary provided to the generic rpm loader:

- dict keys are package versions prefixed by the fedora release and
  edition they have been found (fedora{release}/{edition}/{version}),
  they will be used as branch names targeting releases in the snapshot
  created by the rpm loader

- version fields in dict values are the package intrinsic versions parsed
  from package repository metadata excluding any ".fcXY" suffixes to avoid
  the loader to create multiple releases targeting the same directory,
  they will be used as release names in the snapshot created by the rpm
  loader

Related to T4448