Add support for SCHISM wave model

[SorooshMani-NOAA]

The SCHISM model is supposed to work with both sflux and parametric wind models. It would be useful to have the ability to set it up from here while we're waiting for SCHISM NEMS coupling to be fully implemented.

[SorooshMani-NOAA]

Since right now pyschism doesn't support this feature, we can create an extensions module within coupledmodeldriver and add packages extensions for pyschism, adcircpy, etc. there so that from our standpoint feature is available, and later push these extensions to the respective repositories. e.g. extend pyschism to add WWM support in the extensions module and later prepare that code to be pushed into actual pyschism repo

[SorooshMani-NOAA]

We need the following minimum to get the model running with WWM:

• hgrid_WWM.gr3: since there is no quads in ur mesh this is identical to hgrid.gr3
• wwmbnd.gr3: strictly speaking we should use WW3 as i.c. and b.c. but I’m cheating here with no wave inputs at the boundary. It works fine as the boundary is far from the domain of interest
• wwminput.nml is the WWM main input

Since we need to move to fully coupled WW3 sometime soon, we'll add the minimum required to get this working from the coupledmodeldriver perspective and later when full coupling is implemented remove the extensions code.

[SorooshMani-NOAA]

Since the final goal is full coupling using ESMF or NEMS, for now the ondemand workflow will just hardcode adding WWM model