Add new e/p json based tool for particle flow

Add first version of new tool that loads e/p va json. This is not used in production currently. It will be used for all future iterations of new e/p reference files, to replace hardcoded c++ reference files. I tested that it gives identical FlowElement output to the old style tool. As part of this testing I added a new CA module to run the particle flow physics validation via CA, also included in this MR.