Include npm related files into Makefile and .gitignore

Extedned Makefile in install/ui
 - $ make clean-local removes npm related files in the install/ui directory
Add node_modules and package-lock.json into .gitignore

Fixes: https://pagure.io/freeipa/issue/7278
Reviewed-By: Christian Heimes <cheimes@redhat.com>

install/ui/Makefile.am

@@ -32,3 +32,6 @@ EXTRA_DIST =                            \
 
 install-data-hook:
 	$(INSTALL) -d -m 755 $(DESTDIR)$(appdir)/js/plugins
+
+clean-local:
+	rm -rf package-lock.json node_modules