Add Mend Remediate for dependency management

[dbwiddis]

Description

Adds Mend Remediate (an alternative to GitHub) for dependency management. See https://docs.mend.io/bundle/integrations/page/mend_remediate_and_renovate.html

First option recommended here: https://github.com/opensearch-project/.github/blob/main/RESPONSIBILITIES.md#keep-dependencies-up-to-date

• Will open a "Dependency Dashboard" issue, see example here: Dependency Dashboard flow-framework#6
  • Automatically generates pull requests for dependency updates, marks them if they are impacted by CVEs

Check List

• Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.