EPA plugin enhancements

[dschristianson]

Upgrades to EPA plugin:

• Add failover for when the GeoServer WFS endpoint is offline or times out. Consider back up endpoint for EPA WQX geoserver wfs endpoint that is currently not working #192
• Add configuration for EPA WQP API versions. Current v2.2 is default, v3.0 (still beta) can be configured. Update EPA plugin to use WQX v3.0 web services #191
• Add integration tests for API v2.2
• Updated documentation

Closes #191
Closes #192

Type of change

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

How Has This Been Tested?

• Unit tests
• Integration tests
• Test coverage >= 90%
• Flake8 Tests
• Mypy Tests
• Other -- manual tests

Test Configuration

• Python Version: 3.10

PR Self Evaluation

• My code follows the agreed upon best practices
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests or modified existing tests that prove my fix is effective or that my feature works
• Existing unit tests pass locally with my changes
  - [ ] Any dependent changes have been merged and published in the appropriate modules
• I have performed a self-review of my own code

[vchendrix]

Looks good. I just have some small things about pydocs and documentation. They are minor and don't need a re-review by me if you address them

[dschristianson]

Thanks, @vchendrix! Will address all and push it out the door.