[hathor-fullnode] Create more tests and run them in Github Actions

We should improve testing on our helm charts, by creating more tests and by running them in Github Actions using https://github.com/marketplace/actions/helm-chart-testing and https://github.com/marketplace/actions/kind-cluster.

Example in the real world: https://github.com/Unleash/helm-charts/blob/master/.github/workflows/ci.yaml

Review the Helm chart contents and the linked helm-chart-testing and kind-cluster GitHub Actions, then compare the example .github/workflows/ci.yaml from Unleash. Define chart tests that cover the Hathor fullnode charts and configure GitHub Actions to run them against a kind cluster. Done means the tests run successfully in CI.

Written by the indexing model from the issue text.