Restore PAM user autocreation functionality (#15825) (#15867)

Backport #15825

* Restore PAM user autocreation functionality

PAM autoregistration of users currently fails due to email invalidity.
This PR adds a new setting to PAM to allow an email domain to be set
or just sets the email to the noreply address and if that fails falls
back to uuid@localhost

Fix #15702

Signed-off-by: Andrew Thornton <art27@cantab.net>

* As per KN4CKER

Signed-off-by: Andrew Thornton <art27@cantab.net>

Co-authored-by: 6543 <6543@obermui.de>

routers/admin/auths.go

@@ -239,6 +239,7 @@ func NewAuthSourcePost(ctx *context.Context) {
 	case models.LoginPAM:
 		config = &models.PAMConfig{
 			ServiceName: form.PAMServiceName,
+			EmailDomain: form.PAMEmailDomain,
 		}
 	case models.LoginOAuth2:
 		config = parseOAuth2Config(form)
@@ -346,6 +347,7 @@ func EditAuthSourcePost(ctx *context.Context) {
 	case models.LoginPAM:
 		config = &models.PAMConfig{
 			ServiceName: form.PAMServiceName,
+			EmailDomain: form.PAMEmailDomain,
 		}
 	case models.LoginOAuth2:
 		config = parseOAuth2Config(form)