ADD keycloak group to new users created from odoo

When a subscription requests is confirmed and its related share invoice is fully paid, Odoo creates a new partner, a new Odoo user, and (using the Keycloak API) a new Keycloak user. This MG add the KC user group and the 'lang' KC user attribute to the new KC user during the API call process.

added ToBeMerged label

requested review from @susu105

assigned to @xavier.bonet

merged

mentioned in commit 7a893ac5