Default to not including git hash in build for non ACCESS-OM2 models

[aidanheerdegen]

Removed adding a version hash to every build with the exception of ACCESS-OM* models.

Added --no_version option to also not include version hash in ACCESS-OM builds.

This is necessary because it prevents all of the model types from building outside of a git repository (see #308).

Being able to build from a tarball is desirable for a number of reasons:

1. The code is available as tarballs directly from GitHub
2. Tarballs are the standard way of release code in packages on GitHub
3. spack needs to be able to access code as a tarball from GitHub to enable building specific versions (Is it possible for CI to function if only the git URL is in the SPD? ACCESS-NRI/spack-packages#32), and spack has it's own versioning

Closes #308

[aidanheerdegen]

Hey @aekiss can you take a look and let me know that you're happy for me to merge this?

The idea is it shouldn't affect COSIMA ACCESS-OM2 builds, but will remove the git hash versioning from all other models, and optionally from ACCESS-OM2 if the --no_version flag is used with the ./MOM_compiler.csh script.

CI Compilation was happy enough, but I am testing with a full compile on gadi, with and without the --no_version option. Will report the results when they're complete.

[aidanheerdegen]

Yeah gadi tests are ok. Now to do the same with libaccessom2 ...

[aekiss]

LGTM - just one typo in a comment