Rename packages and package directories to be consistent

[mcgibbon]

Purpose

This PR renames our packages so they all follow the convention pace.<subpackage>, and they all live in a top-level directory named <subpackage>/.

Code changes:

• pace-util is now stored in util
• the fv3core package is now pace.fv3core with package name pace-fv3core
• the fv3gfs-physics package is now pace.physics with package name pace-physics, stored in physics

Infrastructure changes:

• Updated infrastructure to match new package names and locations

Checklist

Before submitting this PR, please make sure:

• [x] You have followed the coding standards guidelines established at Code Review Checklist.
• [x] Docstrings and type hints are added to new and updated routines, as appropriate
• [x] All relevant documentation has been updated or added (e.g. README, CONTRIBUTING docs)
• [x] For each public change and fix in pace-util, HISTORY has been updated
• [x] Unit tests are added or updated for non-stencil code changes

[review-notebook-app[bot]]

Check out this pull request on 

See visual diffs & provide feedback on Jupyter Notebooks.

---

Powered by ReviewNB

[mcgibbon]

launch jenkins

[mcgibbon]

launch jenkins

[mcgibbon]

launch jenkins