Initial implementation of common ReadoutGeometry base for use by InnerDetector and HGTD derived classes. Porting of work done in 21.9 (including ITk and HGTD specific updates) with AthenaMT changes in master.
Removed some methods from DetectorElementBase which (probably) do not belong in Base class, but rather in derived classes. Otherwise, method interfaces should remain as in master with some internal implementation updates. Some additions to the Design class to allow specializations based on the design.
For shifter info:
InDetReadoutGeometry and the new ReadoutGeometryBase classReadoutGeometryBase becomes the base class for InDetReadoutGeometry, and so a number of functions move into the base class. Their implementation should be functionally equivalent, but may not be 100% identical due to a) trying to reduce the remaining use of intermediate CLHEP matrices/vectors/transforms in favour of going straight to Eigen, and b) introducing features needed for ITk/HGTDInDetReadoutGeometry and ReadoutGeometryBase are simply to update the package location from which headers are taken