Add valid years for BC options in gcm_setup to assist with user selection

[acollow]

At the present time, the default option for ocean resolution in gcm_setup is 360x180 however this links to a dataset that was discontinued at the end of 2023. There is no ideal solution to safeguard any BC option as the default but it would be great to display the valid time range for each of the datasets. This would be great to have for the aerosol/chemistry options as well.

[mathomp4]

@acollow Do you know what the date ranges might be? If so, @sdrabenh and myself can look at adding that info. Or I suppose who might know for ocean? (@sanAkel might know?)

As you say, the AMIP emissions is another good place for this sort of info as we know the MERRA2OX dies at some point.

[sanAkel]

Note:

This issue should be marked as related to uncoupled set up of ocean resolution.

Question:

What is the path where 360x180 are located on discover?

Why?

(I can scan that binary file and get you start- end dates).