Helm: Commit a "golden-record" of the chart output

[Logiraptor]

Is your feature request related to a problem? Please describe.

It can be difficult to understand what has changed in a given Helm-chart related PR.

Describe the solution you'd like

We should commit a compiled version of the Helm chart, just like we do for the jsonnet library. A PR check should enforce that the compile step has been run to keep it up to date.

Describe alternatives you've considered

Nothing really

Additional context

This is a prerequisite to support another PR check in the future: automatic diffing between the jsonnet and Helm output.