[Feature]: Support arbitrary start and end months

[forsyth2]

How will this affect the next version number?

New feature (increment MINOR version)

Is your feature request related to a problem?

Yes, for subseasonal-to-seasonal-to-decadal (S2S2D) runs, it is necessary to set specific start and end months, as these simulations do not always start in January (or December). More details can be found in this thread.

Describe the solution you'd like

time-series

ncclimo has --mth_srt and --mth_end options, which are currently not exposed in zppy. We should enable those options via zppy.

climo

Say 1982-05 is the first month. Will ncclimo interpret that as 1982-01? @czender notes that this is the case if zppy "sends an explicit list of valid filenames" but that "If zppy sends the caseid and years to ncclimo and expects ncclimo to generate the filenames then that will fail, since ncclimo will generate the first filename as January and that file does not exist."

The latter is how zppy invokes ncclimo in zppy/templates/climo.bash. Because of that, it seems a refactoring of ncclimo itself would be necessary to support this feature for climo.

Describe alternatives you've considered

No response

Additional context

No response