Move mail to spam when DKIM fails, ignore when white/blacklist and honor other actions

data/conf/rspamd/local.d/force_actions.conf

@@ -0,0 +1,7 @@
+rules {
+  DKIM_FAIL {
+    action = "add header";
+    expression = "R_DKIM_REJECT & !MAILLIST & !MAILCOW_WHITE & !MAILCOW_BLACK";
+    require_action = ["no action", "greylist"];
+  }
+}