MySQL OAF provider

[C-Loftus]

Overview

• Adds a MySQL OAF provider with associated tests
  • MySQL is very similar to postgis but doesn't support the same geospatial functions so it needs some different underlying behavior
• This PR keeps all existing postgres functionality; in doing so it puts all core sql functionality into a base class that both postgres and mysql providers can inherit from; (this could be used for other sql providers in the future if desired)
• Fixed formatting in existing postgis provider to follow the rest of the project (single quotes etc)

Related Issue / discussion

N/A

Additional information

N/A

Dependency policy (RFC2)

• I have ensured that this PR meets RFC2 requirements

Updates to public demo

• I have ensured that breaking changes to the pygeoapi master demo server have been addressed
  • https://github.com/geopython/demo.pygeoapi.io/blob/master/services/pygeoapi_master/local.config.yml

Contributions and licensing

(as per https://github.com/geopython/pygeoapi/blob/master/CONTRIBUTING.md#contributions-and-licensing)

• I'd like to contribute [feature X|bugfix Y|docs|something else] to pygeoapi. I confirm that my contributions to pygeoapi will be compatible with the pygeoapi license guidelines at the time of contribution
• I have already previously agreed to the pygeoapi Contributions and Licensing Guidelines