Adding OLI API (watertap-org#1056)

* add initial oli_api with header

* remove comment

* add initial test for oli_api with watertap usage

* run black

* attempt to resolve readthedocs warning

* attempt 2 to resolve rtd error

* revise header

* temporary removal of oli header

* remove header completely

* bring back header and doc string

* attempt to resolve error again

* revise doc strings

* revise doc strings again to attempt to fix "Definition list ends without a blank line; unexpected unindent."

* run black

* attempt N

* remove unused import

* add test to check create_dbs_dict

* use unittest to check dict

* remove print

* bolster test for create_dbs_dict

* run black

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Co-authored-by: bknueven <[email protected]>