v12: Updates and fixes for SCM

[mathomp4]

This is a PR with fixes for the SCM in v12.

The changes are:

1. Use the git-v12.0 scm inputfiles which moves to GFDL microphysics by default
2. Move to 181 levels by default
3. Set some new sed bits
4. Copy over fvcore_layout.rc into input.nml

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I'm keeping this draft until @narnold1 can test. It works for me in one case at least. If successful for him, we can merge and I can try it out in my nightly testing suite which runs all the cases