Configuration of ATLAS Detector Description using ComponentAccumulator

This merge request introduces code to configure the ATLAS Detector Description using ComponentAccumulator.

Most of the pieces were already there, but code for the Inner Detector has been moved into the appropriate packages under InnerDetector/InDetDetDescr.

It also adds some CI tests to help ensure that the configuration continues to work as the refactoring of the C++ code in the master branch continues.