support to create a wrapper FHiCL file
There are cases were it is needed to override some FHiCL parameters.
For this purpose we can create a wrapper FHiCL file from the original FHiCL file.
A uses case for this is the following:
uBooNE generation stage requires flux files, in the default configuration flux files are distributed through dCache and it is required to be mounted locally.
A wrapper FHiCL file can override this behavior and require the access to flux files through IFDH this way: