feat: multiple domains (#188)

* check uniqueness on create and register user

* change user email, reserve release unique email

* usergrant unique aggregate

* usergrant uniqueness

* validate UserGrant

* fix tests

* domain is set on username in all orgs

* domain in admin

* org domain sql

* zitadel domain org name

* org domains

* org iam policy

* default org iam policy

* SETUP

* load login names

* login by login name

* login name

* fix: merge master

* fix: merge master

* Update internal/user/repository/eventsourcing/user.go

Co-authored-by: Livio Amstutz <livio.a@gmail.com>

* fix: fix unique domains

* fix: rename env variable

Co-authored-by: adlerhurst <silvan.reusser@gmail.com>
Co-authored-by: Livio Amstutz <livio.a@gmail.com>

internal/authz/repository/eventsourcing/handler/user_grant.go

@@ -108,7 +108,6 @@ func (u *UserGrant) processIamMember(event *models.Event, rolePrefix string, suf
 				ID:            u.iamProjectID + member.UserID,
 				ResourceOwner: u.iamID,
 				OrgName:       u.iamID,
-				OrgDomain:     u.iamID,
 				ProjectID:     u.iamProjectID,
 				UserID:        member.UserID,
 				RoleKeys:      member.Roles,