Add an option to liferay-npm-bundler to compose extender portlet JARs

[izaera]

In LPS-83285 we are introducing a portal feature to be able to deploy npm based portlets without any need to use Java tooling at all.

But for that to work, we need some pure JS tool that can compose an OSGi bundle to be deployed in the portal so we have decided to add an option to liferay-npm-bundler so that it creates a JAR with the processed files.