Move Active Physics Schemes to Config

[oelbert]

Purpose

Currently the enabled physics schemes are hardcoded into an "active_packages" list at multiple points in the code. This PR changes that to be set in the physics config in order to enable more physics schemes to be integrated into the model and make this more adaptable.

Code changes:

• docs/physics/state.rst: PhysicsState now takes schemes as an argument, which comes from the PhysicsConfig
• driver/pace/driver/driver.py: get_driver_state now takes schemes as an input in order to pass schemes along to PhysicsState
• driver/pace/driver/initialization.py: all get_driver_state functions now take schemes as an input in order to pass schemes along to PhysicsState
• driver/pace/driver/state.py: PhysicsState needs the active physics schemes in order to initialize, so it is now in the call signature for restart_driver_state and load_state_from_restart
• fv3core/pace/fv3core/initialization/analytic_init.py: MetaEnumStr lives in utils now
• physics/pace/physics/_config.py: schemes is now a member of the config class, with a default value of ["GFS_microphysics"]
• physics/pace/physics/physics_state.py: renamed "active_packages" to "schemes" and "microphysics" to "GFS_microphysics" in preparation for the SHiELD microphysics to be integrated
• physics/pace/physics/stencils/physics.py: Possible physics schemes is an enum class now, changed "active_packages" to "schemes" and "microphysics" to "GFS_microphysics"
• physics/tests/savepoint/translate/translate_driver.py: changed "active_packages" to "schemes" and "microphysics" to "GFS_microphysics"
• physics/tests/savepoint/translate/translate_gfs_physics_driver.py: changed "active_packages" to "schemes" and "microphysics" to "GFS_microphysics"
• physics/tests/savepoint/translate/translate_microphysics.py: changed "active_packages" to "schemes" and "microphysics" to "GFS_microphysics"
• tests/main/driver/test_restart_fortran.py: added schemes to call for get_driver_state
• tests/main/driver/test_restart_serial.py: added schemes to call for get_driver_state
• tests/main/physics/test_integration.py: changed "active_packages" to "schemes" and "microphysics" to "GFS_microphysics"
• util/pace/util/utils.py: Added MetaEnumStr

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

[oelbert]

I'd rather see the Enum used in code, restricting the string form to reading in the config and casting it into the Enum (and error-ing there if doesn't exist).

For example init_zeros would carry a List[PHYSICS_PACKAGE]

Also, do you guys expect to go further an have a normalize API for all physics package?

This feels a little cumbersome but I think is working now. Some sort of standard api for the physics schemes is probably a good idea, I'll bring it up with @fmalatino and @bensonr

[oelbert]

With issues created and/or plans to abstract things away with some oo implementation, I think this is ready to go.

I'll open an issue for it