[meshery/meshery-kuma] Add a Security Insights file for Privateer scan

Many of the assessments in the Privateer scan require a [Security Insights](https://github.com/ossf/security-insights-spec) file to be present in .github folder in the repository.

This [Security Insights](https://github.com/meshery/meshery/blob/master/.github/security-insights.yml) file can be used as a reference.