WIP:
- Added new global scripts folder `global_shared` where global hooks, names and steps will be stored.
- Created new `suite_onboarding` and moved existing test case related to it as a poc.
- Updated all `test.py` files to use global files and fit the new structure.
Note: interaction between clients is not tested here to avoid dependency
on mailserver. When mailserver is mocked more comprehensive tests should
be provided, that is: verify if identity properties are propagated
and read correctly between two different clients.
closes: #6950