[appmesh-grafana] mTLS stats support in the dataplane dashboards

[achevuru]

Issue

NA

Description of changes

Enhance Grafana dashboards to include envoy TLS stats. Grafana dataplane dashboard will now show below stats as well..

• Successful TLS connections
• SSL Failures - Missing Client Cert
• SSL - SAN Verification Failures
• SSL - CA Verification Failures
• SSL Connection errors

Checklist

• Added/modified documentation as required (such as the README.md for modified charts)
• Incremented the chart version in Chart.yaml for the modified chart(s)
• Manually tested. Describe what testing was done in the testing section below
• Make sure the title of the PR is a good description that can go into the release notes

Testing

Installed both Prometheus and Grafana on an EKS Cluster and created an SDS based mTLS mesh. Verified that the newly added stats show up on the dashboard as expected.

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