mbt assemble should take .cfignore into account

[killerfurbel]

When building an mtar via

mbt assemble -m=myapplication.mtar -t=mta-assembly

the .cfignore files within the contained modules are not taken into account.

However, they should be applied similar if I would xs push the corresponding applications.

Since the new ui5-cli 3.x will now also produce -dbg.js and .js.map files in the minify task, I don't want to deploy them to production. Putting them into the .cfignore helps with xs push, but not when creating a .mtar and deploy it via xs deploy.