ATLIDTRKCP-370: Computing local to global transformation only one time for pixel clusters
Description: This MR avoids to repeat the local to global transformation multiple times for pixel clusters. The global position is computed now only once during pixel cluster creation and passed to the pixel cluster object that stores it internally. The position is then simply retrieved during the pixel space point creation instead of being recomputed.
This is done by introducing new constructors, for both the PixelCluster and SiCluster objects, that accept both local and global position. In the previous version of the code only the local position was passed and the constructor was taking care of computing the global position, which was then cached inside the SiCluster object.
Thus, in the space point maker tool it seems save to assume that the cluster has a global position since it is computed if the SiCluster has a detector element, and that is the case in the space point maker.
JIRA: ATLIDTRKCP-370