Update diagnostics for CMIP7

[mnlevy1981]

There is a CMIP7 Data Request tool that can be used to determine what output is needed for a given experiment. When the output lists have been finalized, we need to make sure that MARBL has a mechanism for providing the correct diagnostic list to the GCM. One possibility would be to introduce a new cmip7 diag_mode between minimal and full (presuming minimal is already a subset of the CMIP requirements). A second option would be GCM specific, but we could create a suite of marbl_diagnostics files based on the CMIP requests and then rely on the GCM to provide a mechanism to use one of those files instead of generating marbl_diagnostics based on the YAML file.