Issue #3498739 - Allow returning a 403 response when blocking

Closes #3498739

config/install/restrict_ip.settings.yml

@@ -18,6 +18,9 @@ allow_role_bypass: false
 # A key indicating what action should be performed when bypasses are allowed by role, but users are not logged in
 bypass_action: 'provide_link_login_page'
 
+# A boolean indicating whether to return a 403 access denied response when blocking.
+return_403: false
+
 # D7 variable - restrict_ip_white_black_list
 # An integer indicating how to check bypass restrictions.
 #   0 = check access on all paths