TT-12363 Add support for OIDC configuration options in `apiDefinition`

[djablonski-moia]

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Add support for the openid_enabled and openid_options properties in apidefinitions, so APIs using this feature can be created via Tyk Operator..

Expected Behavior

Potential BDD Test Coverage

Feature: Support OpenId Connect settings in ApiDefinition custom resource
  In order to utilize  OpenId Connect for authentication
  As a developer
  I need to be able to configure an api to contain the required properties

  @grpc
  Scenario: OIDC configuration
    Given there is a ./custom_resources/httpbin.oidc.apidefinition.yaml resource
    When I request /httpbin-oidc/headers endpoint
    Then there should be a 200 http response code

Current Behavior

It''s simply not possible to configure these properties at the moment (but also documented not to be supported), but it makes usage of Tyk Operator impossible when you need this feature.

Possible Solution

Implement support for these properties.

Additional Context

We added an OpenId Connect use case recently, while we were already using Tyk Operator. We would need to drop using it and implement all apidefinition handling ourself without the support in the operator.

We are willing to invest into this, and we will start working on a PR to add this support soon, in order to support our use case (and those of others who also want/need this).