Design unix group authentication flow

[gcurbelo123]

[gcurbelo123]

@kevinpricethesecond
Initial thoughts:

1. Modify the "ldap" custom_idp_configuration for a tenant to include a unix_groups_supplemental_filter object
2. Modify get_tenant_user to add check for unix_groups_supplemental_filter
3. If present, use this in the final user_search_filter

Things we will need:
search_filter = '(objectClass=posixGroup)' to get the list of groups, go through that to retrieve users in a group

[kevinpricethesecond]

Test method::

setup:
update custom_idp_config directly in db:

dlogin authenticator_postgres_1
psql -Uauthenticator -x
SELECT * FROM tenantconfig WHERE tenant_id='tacc';
UPDATE tenantconfig SET custom_idp_configuration='{"ldap": {"unix_groups_supplemental_filter": "(cn=G-827613)"}}' WHERE tenant_id='tacc';
## make sure it worked
SELECT * FROM tenantconfig WHERE tenant_id='tacc';

tests:

1. try login with a user in the group
2. try login with a user not in the group
3. try login with incorrect custom_idp_configuration:: '{"ldap": {"unix_groups_supplemental_filter": "(cn=G-000000)"}}'
4. try login to different tenant without the custom_idp_configuration