This commit adds the validation in the ``metadata.Delegations``
to prevent that one of the delegate role names given is a top-level
role name.

A ``ValueError`` will be raised if one of the roles names in the
list given to as delegated contains the role name as one of the
top-level roles.

Signed-off-by: Kairo de Araujo <kdearaujo@vmware.com>

- Reuse the dataset and the existing tests
- Fix the keyids in the tests datasets to be aligned
- Fix the ``ValueError`` message aligned to the existent messages

Signed-off-by: Kairo de Araujo <kdearaujo@vmware.com>

- Add the check for empty strings in the Delegate Role name
- Remove the comprehensive lists to make the code more readable
- Remove the test for empty file name from
``test_updater_with_simulator``

Signed-off-by: Kairo de Araujo <kdearaujo@vmware.com>

The set() is not required in the OrderedDict.

Signed-off-by: Kairo de Araujo <kdearaujo@vmware.com>