XIOS: Account for filename patterns

[joewallwork]

Filename patterns are not currently supported in our XIOS implementation. This would likely make use of setFileSplitFreq and getFileSplitFreq.

Originally posted by @jwallwork23 in #846 (comment)

[joewallwork]

Ideally, the restart files should go through the same config as the non-XIOS implementation

model.restart_file
string           (default = restart%Y-%m-%dT%H:%M:%SZ.nc)
The file name or file name pattern to be used for the output restart files. A fixed name can be used, which will be overwritten every time a restart checkpoint is created. Otherwise the file name may include formatting codes supported by the C/C++ time library to create a new file at every restart checkpoint.