validate the initial condition data

[nbren12]

There are some simple checks we could perform on the initial condition data to make sure it is compatible with the fv3gfs. Here are a couple of examples:

• The restart files need to only contain float values, otherwise the model errors out.
• The grid needs to match the one specified in the input.nml.

Ultimately, this feature should probably be part of a bigger refactor of the representation of the initial condition data to a richer python object.

[mcgibbon]

FV3Config: Validate initial conditions data

[oliverwm1]

Agreed some checking on initial condition data would be useful. This is one aspect of what I suggested in #6 although we got a little sidetracked in that issue.