Include test cases with the config of environment

[pierre-rouanet]

1. Each environment should provide a method to create its specific test cases (depending on the config).
2. When creating an experiment pool with the form_settings factory you can provide a test cases which will be used for all experiments
3. If you provide a test cases with different environment (or config) should raise an Error

[clement-moulin-frier]

TODO:

• add generator from acutal updates of the environments
• remove default arm config from testcases in simple_arm