Add newly created users after a LDAP authentication to group Analysts

[c8y3]

When IRIS_AUTHENTICATION_CREATE_USER_IF_NOT_EXIST is true and the authentication type is ldap, then users that do not yet exist in the IRIS database are automatically created during their first login.
This is a proposition to also add these newly created users into the group Analysts. Otherwise, they can't do much with the tool.
This suits best to our current use-case. However, there are probably alternatives. For instance, the default permissions/groups could be configurable, or maybe extracted from the ldap...

Note: in order to avoid code duplication, I introduced method ac_get_group_analysts in app.iris_engine.access_control.utils (it's called from both the post_init and ldap_handler). However, I hesitated about where to put this method: it may equally well find itself in app.datamgmt.manage.manage_groups_db, or yet some other place...

[whikernel]

Hi @c8y3

Thanks for the PR! Indeed, this change might be a little too specific. Something we'd like to add is the ability to map a LDAP group to an IRIS group. That would be more flexible.

What do you think?

[c8y3]

Yes, indeed that's right.
Maybe, as an intermediate more flexible step what about having the possibility to configure the group into which newly created users will be added? To that end, I modified this PR with the addition of the configuration variable IRIS_NEW_USERS_DEFAULT_GROUP.
Let me know what you think.

[whikernel]

It is indeed! Thanks :)