New 'module_stream' optional parameter
- Implement new optional parameter module_stream to allow a scratch module
build's stream name to be set from the command line when also submitting a
YAML modulemd file.
- Validate that module_name and module_stream parameters can only be specified
along with a YAML modulemd file.
- Add tests to verify that module_stream sets the stream name correctly.
- Add tests to verify that module_name and module_stream are only allowed along
with a YAML modulemd file.
Signed-off-by: Merlin Mathesius <mmathesi@redhat.com>