Module manifest should support JSON in addition to XML

[isc-kiyer]

There should be backward compatibility so we always first check for the existence of module.json and if not present, fall back to module.xml. With JSON would be good to have a schema as well available in github that users can link to using $schema and get intellisense. For server-side editing, would want a new studio document to view the JSON version.

Internal issue: HSIEO-6645.

Related to #502