Add check for LDAP group membership (#10869)

This is a port of gogs/gogs#4398

The only changes made by myself are:

Add locales
Add some JS to the UI
Otherwise all code credit goes to @aboron

Resolves #10829

Signed-off-by: jolheiser <john.olheiser@gmail.com>
Co-authored-by: zeripath <art27@cantab.net>

modules/auth/auth_form.go

@@ -30,6 +30,11 @@ type AuthenticationForm struct {
 	SearchPageSize                int
 	Filter                        string
 	AdminFilter                   string
+	GroupsEnabled                 bool
+	GroupDN                       string
+	GroupFilter                   string
+	GroupMemberUID                string
+	UserUID                       string
 	RestrictedFilter              string
 	AllowDeactivateAll            bool
 	IsActive                      bool