scripted-diff: Replace gArgs with local argsman

-BEGIN VERIFY SCRIPT-
sed -i -e 's/gArgs.Add/argsman.Add/g' `git grep -l "gArgs.Add"`
-END VERIFY SCRIPT-

src/dummywallet.cpp

@@ -27,7 +27,7 @@ public:
 
 void DummyWalletInit::AddWalletOptions(ArgsManager& argsman) const
 {
-    gArgs.AddHiddenArgs({
+    argsman.AddHiddenArgs({
         "-addresstype",
         "-avoidpartialspends",
         "-changetype",