Add assets for Cisco SD-WAN integration

[TCheruy]

What does this PR do?

Add assets for the Cisco SD-WAN integration Includes:

• One dashboard
• Three monitors
• A readme doc
• Metrics metadata

Motivation

Additional Notes

Review checklist (to be filled by reviewers)

• [ ] Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• [ ] Changelog entries must be created for modifications to shipped code
• [ ] Add the qa/skip-qa label if the PR doesn't need to be tested during QA.
• [ ] If you need to backport this PR to another branch, you can add the backport/<branch-name> label to the PR and it will automatically open a backport PR once this one is merged

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