Example of converting GPU algorithm to Triton custom backend

[kpedro88]

1. pick a classical algorithm (e.g. HCAL reconstruction) that has already been ported to CUDA
2. get GPU code for that algorithm
3. set up custom backend using library for that algorithm
4. set up associated Sonic producer to handle inputs/outputs
5. document procedures for steps 3 and 4

assigned to: @violatingcp, ?

[kpedro88]

@pierinim are you interested in this?