Common ReadoutGeometry Base Class for InDet and HGTD (SolidStateReadoutGeometry)

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:

• The substantive changes are limited to InDetReadoutGeometry and the new ReadoutGeometryBase class
• ReadoutGeometryBase 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/HGTD
• The changes outside InDetReadoutGeometry and ReadoutGeometryBase are simply to update the package location from which headers are taken

DetectorDescription/ReadoutGeometryBase/ReadoutGeometryBase/SolidStateDetectorElementBase.h

@@ -197,25 +197,6 @@ namespace InDetDD {
     void setCache();
     //@}
 
-    /**
-     * @name Navigation setters
-     * Non-const methods.
-     * These are inline methods and set neighbours.
-     */
-    //@{
-    void setNextInEta(const SolidStateDetectorElementBase* element);
-    void setPrevInEta(const SolidStateDetectorElementBase* element);
-    void setNextInPhi(const SolidStateDetectorElementBase* element);
-    void setPrevInPhi(const SolidStateDetectorElementBase* element);
-    /**
-     * @name Navigation
-     * Inline methods to access neighbours.
-     */
-    //@{
-    const SolidStateDetectorElementBase* nextInEta() const;
-    const SolidStateDetectorElementBase* prevInEta() const;
-    const SolidStateDetectorElementBase* nextInPhi() const;
-    const SolidStateDetectorElementBase* prevInPhi() const;
     /**
      * @name Common items
      * Inline method
@@ -233,11 +214,13 @@ namespace InDetDD {
     /**
      * identifier of this detector element (inline)
      */
+    //do these need to be virtual? - they are in 21.9 but I don't see why
     Identifier identify() const;
     
     /**
      * identifier hash (inline)
      */
+    //do these need to be virtual? - as above
     IdentifierHash identifyHash() const;
     
     /**
@@ -440,7 +423,8 @@ namespace InDetDD {
     /**
      * access to the local description (inline):
      */
-    const DetectorDesign& design() const;
+    
+    virtual const DetectorDesign& design() const;
     
     virtual const Trk::SurfaceBounds& bounds() const;
     /**
@@ -582,7 +566,7 @@ namespace InDetDD {
     /**
      * Recalculate cached values.
      */
-    void updateCache() const;
+    virtual void updateCache() const;
     
     /**
      * Calculate extent in r,z and phi. The values are cached and there
@@ -688,20 +672,6 @@ namespace InDetDD {
      * hash id of this detector element
      */
     IdentifierHash m_idHash{};
-
-    //not for base class?
-    //bool m_isPixel{false};
-    //bool m_isDBM{false};
-    //@}
-
-    /**
-     * @name Variables set by individual setter methods
-     */
-    //@{
-    const SolidStateDetectorElementBase* m_nextInEta{nullptr}; // set by setNextInEta
-    const SolidStateDetectorElementBase* m_prevInEta{nullptr}; // set by setPrevInEta
-    const SolidStateDetectorElementBase* m_nextInPhi{nullptr}; // set by setNextInPhi
-    const SolidStateDetectorElementBase* m_prevInPhi{nullptr}; // set by setPrevInPhi
     //@}
 
     /**