Add configuration options for custom DNS work.

[barbacbd]

The work relates to the enhancement openshift/enhancements#1468. The AWS, Azure, and GCP platform status structs are updated to include custom DNS options. The internal and external load balancer ip addresses as well as the types of dns records make up the base of the data.

[openshift-ci]

Hello @barbacbd! Some important instructions when contributing to openshift/api:
API design plays an important part in the user experience of OpenShift and as such API PRs are subject to a high level of scrutiny to ensure they follow our best practices. If you haven't already done so, please review the OpenShift API Conventions and ensure that your proposed changes are compliant. Following these conventions will help expedite the api review process for your PR.

[barbacbd]

/hold

[barbacbd]

/cc @sadasu
/cc @patrickdillon
/cc @JoelSpeed

[openshift-ci]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: barbacbd
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[openshift-ci]

@barbacbd: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
ci/prow/integration	76867ec	link	true	/test integration

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