feat(ci test): add testing for helm chart

[tamcore]

• Manually setting --set=image.repository=ghcr.io/${{ github.repository }} for this CI job, so the image is pulled from Github instead

• If the workflow is manually triggered (github.event_name == 'workflow_dispatch'), it will not check for changes made to the chart and simply force a run

• Fail with invalid YAML

  • https://github.com/tamcore/dragonfly/actions/runs/3801483178/jobs/6465998892

• Fail with broken PodSpec

  • https://github.com/tamcore/dragonfly/actions/runs/3801584857/jobs/6466201901

• Pass, as PR doesn't change chart

  • https://github.com/tamcore/dragonfly/actions/runs/3801652981/jobs/6466348221

• Pass, as PR changes chart but does not break it

  • https://github.com/tamcore/dragonfly/actions/runs/3801698388/jobs/6466447398