[tools] Adds generate.sh

generate.sh is a helper script that calls themehelper and
move the file automatically.

tools/themehelper/README

@@ -7,3 +7,5 @@ How to use the components generator
 5. qmlRegisterUncreatableType the new created components in qquicknemostyleextensionplugin.cpp and 
    adds them in the style.pro file
 6. update theme files if needed
+
+You can also run ./generate.sh in the tools folder instead of doing 3 and 4.

tools/themehelper/generate.sh

+#!/bin/sh
+./themehelper.py components.json
+mv *.h ../../src/styles/autogenerated/
+mv *.cpp ../../src/styles/autogenerated/