Draft: RICH simulation in RUN5 using DD4HEP from May06-2024

This contains a new RICH detector simulation package named GaussOptix in the DD4HEP framework. This branch is created from lhcb-sim11-dev as of May06-2024.
This package is intended for the simulation of RICH in RUN5. The design of the RICH system for RUN5 is expected to evolve in the coming years and its simulation needs many new features to be introduced. The plan is to keep the package named GaussPhotonics stable for simulating RUN3 and keep it independent of GaussOptix. It is envisaged to have all the new developments related to RUN5 in GaussOptix. This package re-uses software from GaussPhotonics for the aspects where this is appropriate. This update uses the Detector MR !553 (merged) which contains some of the geometry designs for RICH in RUN5. This MR is compatible with Gauss MR !1040 in the sense that all the updates in that MR as of May06-2024, are included in this branch. Hence, as of May07-2024, this MR can be merged after merging MR !1040. This package has protections implemented regarding ‘RICH specific’ optical processes. As a result, any other sub detector in RUN5 can use optical processes that are different than what is implemented here, and there will be no interference between the simulation of RICH and that of the other sub detector. This package stores various information into the standard output in a standard way including the information related to RICH hits and the corresponding charged tracks. An example of the ‘options file’ used for running this and an example of the logfile (compressed) obtained are attached to this MR. Integration of RICH simulation into Gauss involves updating some of the python configuration scripts in the Gauss area. This branch contains those updates also. These are made from the master version of Gauss as of May06-2024. In the future it is possible that these scripts evolve in the master area and hence this branch becomes out of sync with the master branch. In this context, occasionally attempts will be made to re-base and thus and update these scripts in this branch to resolve this issue.