Remove legacy src/ccpp_api.F90 - contains #445 (fix metadata2html.py) and #447 (remove NEMSfv3gfs test scripts)

[climbfuji]

Remove legacy src/ccpp_api.F90.

Note. This PR now (04/10/2022) also contains the changes from #445 and #447 (all approved).

User interface changes? Yes

Models currently importing ccpp_t from ccpp_api must get it from ccpp_types directly.

Fixes #442

Testing:

I ran the two tests that Julie set up a while back for ccpp_prebuild.py in directory tests, both of them passed:

> PYTHONPATH=/Users/dom.heinzeller/scratch/ufs-weather-model/ufs-weather-model-split-gfs-typedefs/FV3/ccpp/framework/scripts/parse_tools:/Users/dom.heinzeller/scratch/ufs-weather-model/ufs-weather-model-split-gfs-typedefs/FV3/ccpp/framework/scripts:$PYTHONPATH python3 test_metadata_parser.py
> PYTHONPATH=/Users/dom.heinzeller/scratch/ufs-weather-model/ufs-weather-model-split-gfs-typedefs/FV3/ccpp/framework/scripts/parse_tools:/Users/dom.heinzeller/scratch/ufs-weather-model/ufs-weather-model-split-gfs-typedefs/FV3/ccpp/framework/scripts:$PYTHONPATH python3 test_mkstatic.py

The change is also being tested by the ufs-weather-model regression testing system, see ufs-community/ufs-weather-model#1130

[gold2718]

Whew! Finally made it through this review.
Looks okay :)

[grantfirl]

This looks fine to me. Thanks for pointing out in the description that SCM will need to import ccpp_t from ccpp_types now. I'll make that change in an upcoming PR.