Update ACHEM to new MAPL ACG

[mathomp4]

This issue is prompted by @pcolarco who is looking at ACHEM. He said:

This is a different, maybe ExtData question. You can point me at Ben if he is back around: I am looking at the @achem component in a recent model. There is some functionality that depends on an import CO_BIOMASS_VOC being filled. The import is not defined in the ACHEM_Registry.rc (or anywhere else I can see) but it is given an entry in the ACHEM_ExtData.yaml. Seemingly the code works in that it produces sensible looking output. Could this make any sort of sense?

I looked and this repo seems to be "partially" ACG-ified and it's the old Perl ACG. And there is a ACHEM_Registry.rc file but looking at the GC, it's only really used for exports? I think it was "abandoned" because ACHEM has a lot of Imports, etc. that are only active if a condition is met. Like, say CO_BIOMASS_VOC:

    OPTIONAL_VOC_IMPORTS: if (self%voc_chem) then

     if (.not. self%mam_chem) then
        call MAPL_AddImportSpec(GC, &
                                SHORT_NAME = 'OH',  &
                                LONG_NAME  = 'Hydroxyl radical (OH)',  &
                                UNITS      = 'mol mol-1', &
                                DIMS       = MAPL_DimsHorzVert,    &
                                VLOCATION  = MAPL_VLocationCenter,    &
                                RESTART    = MAPL_RestartSkip, &
                                __RC__)
     end if

        call MAPL_AddImportSpec(GC, &
                                SHORT_NAME = 'CO_BIOMASS_VOC',  &
                                LONG_NAME  = 'CO Biomass Burning Emissions',  &
                                UNITS      = 'kg m-2 s-1', &
                                DIMS       = MAPL_DimsHorzOnly,    &
                                VLOCATION  = MAPL_VLocationNone,   &
                                RESTART    = MAPL_RestartSkip, &
                                __RC__)

So in a StateSpecs file that OH would need some self%voc_chem .AND. (.NOT. self%mam_chem) column?

Luckily, @darianboggs has made the new ACG much more useful and it has the ability to have specs with if-logic. MAPL3 will be ACG-heavy, so it might be worth converting ACHEM to new ACG with MAPL2 now and making sure we get that right and then converting to MAPL3.