Enable mwext-TemplateData-npm job

Also disable mwext-TemplateData-jslint in most pipelines (kept
in 'check' pipeline so that for new users a basic check is still
run though it might use a different version of jshint, whichever
is globally installed).

Change-Id: I882e3fa57b2e5e3de01c2f77b832c205ababf719