Generate images-core.txt with each Big Bang release

Feature Request

Why

Currently add-on images are included in the images.txt artifact with each Big Bang release. This makes for a lot of additional images that are not needed in many customer environments.

Separating out the minimum images needed for core into their own images.txt artifact would make automation much easier for the integration engineers.

Proposed Solution

Create a separate images.txt with just the core images listed in it that is generated as an artifact with each BB release.