Set general project once for all like with `set_gitlab_connection()`

[statnmap]

• [ ] Explore how set_gitlab_connection() works and propose a similar way to set a project for the entire session.

This is to avoid fun(project = my_proj) each time.

• [ ] This means we need to list all function requiring a project, and add th function that retrieves the global project number if missing(project)
• [ ] Create at least a unit test to test both way a new functions added