feat: EmptyAppOptions implement DynamicConfig (#23440)

testutil/sims/app_helpers.go

@@ -283,6 +283,8 @@ func GenesisStateWithValSet(
 	return genesisState, nil
 }
 
+var _ server.DynamicConfig = EmptyAppOptions{}
+
 // EmptyAppOptions is a stub implementing AppOptions
 type EmptyAppOptions struct{}
 
@@ -291,6 +293,11 @@ func (ao EmptyAppOptions) Get(o string) interface{} {
 	return nil
 }
 
+// GetString implements AppOptions
+func (ao EmptyAppOptions) GetString(o string) string {
+	return ""
+}
+
 // AppOptionsMap is a stub implementing AppOptions which can get data from a map
 type AppOptionsMap map[string]interface{}