Extra params fixes #1667

[Moritz-Langer]

Overview

This PR contains the necessary adjustments for passing extra_params to providers and allow for custom behaviour in plugins.

Related Issue / discussion

Fixes #1667

Additional information

In the itemtypes a new variable is introduced. It contains a dictionary with unknown request parameters, basically anything can be passed to the request without changing behavior except there are no errors facing the client. The variable extra_params is then passed to the providers and accessible there.
Another oracle specific change is the provider definition is getting passed to the manipulation class for possible adjustments to queries and filtering using the geometry column. Because it could also be named diffenently the name must be accessible later on.

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

[tomkralidis]

Note: OGC API - Features supports additional query parameters that are not defined in OpenAPI via vendorSpecificParameters, which pygeoapi natively supports on OpenAPI generation for feature/record .../items definitions.

As a result, this PR was updated to support this approach on queries to itemtypes (which now applies to all feature/record providers). This PR was also tested against OAFeat CITE with no impact to conformance.