Resolve "DataContainer should include the ensemble macrostate variables as inmutable parameters"

Description

• Remove ensemble static data from BaseEnsemble._get_ensemble_data and added to the new created BaseEnsemble.ensemble_parameters
• Ensemble parameter are positionals
• Added number of atoms to .ensemble_parameters
• Removed add_parameters
• Metadata is created in BaseEnsemble and includes seed
• DataContainer initializes from atoms, ensemble_parameters and metadata
• Exception is raised when ensemble is loaded from DataContainer file with non-compatible ensemble_parameters

Unittest and docstring have been updated accordingly.

Closes #295 (closed)