Update CCPP constituents object stub to include diag_name; other updates

[jimmielin]

Issue Type

Infrastructure Update

Issue Description

As reminded by @peverwhee during Monday hackathon 3/9/2026

In order to use atmos_phys beyond the current tag (atmos_phys0_21_000), the CAM stub for ccpp_constituent_prop_mod.F90 needs to be updated to accept diag_name in the %instantiate call.

This is just a stub update - there are no answer changes.

This should be brought in together with whatever next PR changes the atmos_phys external (which I think/hope is #1445)

Will this change answers?

No

Will you be implementing this yourself?

Yes