pygeoapi provider plugin for Climsoft

[isedwards]

1. Create a pygeoapi provider (see docs and code) to allow pygeoapi to retrieve data directly from Climsoft's MariaDB database.
2. Test with data from mariadb_climsoft_test_db_v4
3. Create documentation for someone who uses pygeoapi, but is new to pyopencdms, to be able to run the required docker container for local climsoft DB and use the Climsoft provider with pygeoapi

See also #52