CAM could sparse-checkout shared aerosol infrastructure files from CAM-SIMA (or MIAM)

### Issue Type

Infrastructure Update

### Issue Description

After #1506 the following files are exact copies between CAM and CAM-SIMA:
```
diff ... | wc -l:

aerosol_optics_core.F90 0
aerosol_optics_mod.F90 0
hygro_aerosol_optics_mod.F90 0
hygrocoreshell_aerosol_optics_mod.F90 0
hygroscopic_aerosol_optics_mod.F90 0
hygrowghtpct_aerosol_optics_mod.F90 0
insoluble_aerosol_optics_mod.F90 0
refractive_aerosol_optics_mod.F90 0
volcrad_aerosol_optics_mod.F90 0

aerosol_properties_mod.F90 0
modal_aerosol_properties_mod.F90 0
bulk_aerosol_properties_mod.F90 0
```
in CAM they are in `src/chemistry/aerosol`
in CAM-SIMA they are in `src/aerosol`

the following files have minor differences that can be resolved
```
radiative_aerosol_definitions.F90 35
- I think I changed shr_kind_cl to 256 in SIMA because CCPP-framework
was complaining about it.
```

The `aerosol_state` versions have MMR handling differences between CAM and CAM-SIMA and should not be merged.

It would be nice to have one true source for these files and we could sparse-checkout them from the CAM-SIMA repository into CAM. That would complicate tagging a bit if we want to make changes, though, so I am just opening for discussion for now.

### Will this change answers?

No

### Will you be implementing this yourself?

Yes