[#65625634] Move config to core

Requires https://github.com/alphagov/vcloud-core/pull/13 to have already been merged.

This PR removes the config loader and config validator that are in tools and uses instead the config loader and validator that are in core (as of https://github.com/alphagov/vcloud-core/pull/13).

There are two things missing here:
  - There were tests for the schemas in the config loader. I think it's appropriate to test the schemas here, not in core, but now that config loader is elsewhere, they will require reimplementing. I've added a task to the story.
  - I've commented out the vcloud-launch test which relies heavily on the config loader and doesn't allow injection of the loaded config. The solution is to allow injection of the loaded config, but that is a big refactor so it makes sense to do this separately to avoid over-complicating this PR. Again, I've added that as a task to the story.

The integration tests pass.