Policy change - Move any core im classes to VA that are not used by VRS, Cat-VRS

[larrybabb]

During the efforts to get the VA, Cat-VRS and GKS-Core 1.0 Trial Use ballots ready for review the GKS tech leads determined that we would only promote classes to the GKS-Core repo that were being used or had the high likelihood of every being used in VRS and Cat-VRS. This meant that all classes from the GKS Core IM that are only utilized in VA would be moved to the VA-spec base level schema.

While this is a significant shift from a recent previous decision the idea is that during this v1.0 effort to get some early driver projects and implementers enough stability to get started, that we would not try to future-proof or try to predict how and where classes might actually end up in the longer term. The primary focus for the 1.x timeframe is to work on a minimalistic set of sound principles for data engineers to begin using the classes without considerable concern of clear purpose and use of the classes in the near term. As we being early adoption we will learn how to improve and potentially reorganize the classes, but we should be able to do so without breaking the 1.x version of these products.

As a result of the above policy, the VA specific core-im classes were moved back to the va-spec/schema/base/va-spec-source.yaml file.