Finish datastream

[iperetz-goo]

Add missing fields and behavior from recently implemented Datastream Stream resource #6806

Changes:

1. Add Postgres & Oracle source configs
2. Call an additional update after create stream if the desired_state was RUNNING.
3. Add support for validation results in operation errors

This PR was re created after #7115 was accidentally deleted

If this PR is for Terraform, I acknowledge that I have:

• Searched through the issue tracker for an open issue that this either resolves or contributes to, commented on it to claim it, and written "fixes {url}" or "part of {url}" in this PR description. If there were no relevant open issues, I opened one and commented that I would like to work on it (not necessary for very small changes).
• Generated Terraform, and ran make test and make lint to ensure it passes unit and linter tests.
• Ensured that all new fields I added that can be set by a user appear in at least one example (for generated resources) or third_party test (for handwritten resources or update tests).
• Ran relevant acceptance tests (If the acceptance tests do not yet pass or you are unable to run them, please let your reviewer know).
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[ScottSuarez]

duplicate of #7175