`inp_filepath` usage

[efletcherPIFSC]

inp_filepath is set from reading INP files to agepro_inp_model this is used to as a store the AGEPRO input file that was imported from.

Questions

• Should this value be extended to be used to other functions ageproR::run_agepro (Launch AGEPRO model binary with AGEPRO Input file)
• Should inp_filepath be a private value?
• Should it be name be refactored to reflect the original intention: the AGEPRO Input File filename that read_inp read from?