[SIEMINT-81] DDSaaS: Mailchimp: Crawler Integration v1.0.0

[akaila-crest]

What does this PR do?

This is a initial release PR of Mailchimp integration including all the required assets.

Additional Notes

• Crawler code for this integration has been committed in its respective repo
• The assets are available in our sandbox and can be shared separately with the required teams.

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

[jhgilbert]

I've filed a ticket for docs team review. Thank you!

[dj0well]

i removed the no-seploy label since the pr w/o asset is merged (https://github.com/DataDog/integrations-core/pull/18262) cc: @mgarabed @michellealbright12 @BoyangHuang