CompoundConfig ctors incompatible with invoking Accelergy as subcommand

[gilbertmike]

Only one of three CompoundConfig ctors populate the inFiles member. However, the inFiles member is used as an argument to invoke Accelergy as a subcommand. The CompoundConfig ctor that does not load from a file is specifically incompatible with this method for invoking Accelergy.

Currently, my solution is to have PyTimeloop call Accelergy and ensure that the config passed to Timeloop already includes ERT and ART keys.

I think perhaps calling Accelergy should be handled not in the model app (or, at least not in the constructor), but in main since file input is specific to using the Timeloop binary.

[angshuman-parashar]

I think it's ok to remove Accelergy calls from the C++ application. Accelergy calls can be in PyTimeloop. The C++ application either takes in an ERT or uses the legacy PAT model interface.