Create access-om3 SBD that houses the equivalent SPD

[CodeGat]

See ACCESS-NRI/ACCESS-OM3#3 (comment)

Essentially, we will need an overarching access-om3 SBD. This will be used to version the entirety of an access-om3 deployment release, including not only the access-om3 package, but the dependencies, the versions of spack-{packages,config} and the spack.yaml itself. This is similar to https://github.com/ACCESS-NRI/access-om2.

Currently we are leaning towards having the naming scheme as follows:

• SBD: access-om3-virtual
• SPD: access-om3

References ACCESS-NRI/ACCESS-OM3#3
References ACCESS-NRI/ACCESS-OM3#2