Add an Optical WLS

[whokion]

Add an optical warelength shift (WLS) interactor and an associated test:

• Add data and params for WLS
• Implement an interactor and tests for WLS
• Add secondary photon memory allocation in the optical Interact

This is an initial implementation of an optical wavelength interactor based on the G4OpWLS process with a couple of differences:

• Uses an inverse cumulative distribution for sampling the re-emitted photon spectrum replacing the rejection technique used in Geant4.
• Supports only an exponential time structure for remitted photons for now, which will be extended for a general time structure later (depending on whether we support two WLS processes similar to Geant4 and use configurable (run-time) options for the re-emitted time structure".

[github-actions]

Test summary

 3 877 files   5 969 suites   4m 9s ⏱️
 1 603 tests  1 575 ✅ 28 💤 0 ❌
19 857 runs  19 782 ✅ 75 💤 0 ❌

Results for commit 390793f.

♻️ This comment has been updated with latest results.

[sethrj]

Really nice work! I've got a couple of suggestions; if you want I can write the CDF sampler class.

[whokion]

@sethrj Thanks a lot for your review and comments. I addressed most of them, but left a couple of suggested improvements to you (a CDF sampler class and the integrate_trapezoid utility function). Sorry for asking additional help - I will be away for a week, but should catch up any other suggestion later.

[amandalund]

Great work @whokion!

[whokion]

@sethrj can you help how to fix the compilation error from build-spack / orange-float-g4@11.0? Thanks.

[sethrj]

@whokion I've fixed the floating point error and added a couple of to-dos. Could you please take a look at the remaining discussion?

[hhollenb]

Pending Seth's and Amanda's suggestions, I think it looks good!

[whokion]

@sethrj Thanks a lot for fixing the float issue and adding other notes. Besides the discussion for adding a model or models which can be revisited in the next MR, it would be great that we can merge this as it is. Thanks again!

[sethrj]

@amandalund If you're satisfied then please merge!

[sethrj]

Thanks for the new model! I've added the little "todo" tasks to #1263 .

[amandalund]

Excellent, thanks @whokion!