Implement Domain update code path

[razor-1]

Issue #, if available:
aws-controllers-k8s/community#1181

Description of changes:
This implements Domain update support for the opensearchservice controller.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[ack-prow]

Hi @razor-1. Thanks for your PR.

I'm waiting for a aws-controllers-k8s member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[a-hilaly]

/ok-to-test

[a-hilaly]

This is great! Thank you so much @razor-1! I left one comment in-line

[a-hilaly]

Can we add a simple test case for updating a domain CR? either a new test or updating an existing one should be good.

[razor-1]

yes, good call. Added.

[a-hilaly]

Thank you so much @razor-1 !

Can you please send a release PR? Just running this command will generate the artifacts :)

RELEASE_VERSION=v0.0.26 ./scripts/build-controller-release.sh opensearchservice

/lgtm

[ack-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: a-hilaly, razor-1

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