Added model_generator file

Author: vanlooverenkoen

example/tool/model_generator.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+
+CURRENT=`pwd`
+DIR_NAME=`basename "$CURRENT"`
+if [ $DIR_NAME == 'tool' ]
+then
+  cd ..
+fi
+
+fvm flutter packages run model_generator