Move Helm chart back to this repo

[sagikazarmark]

Updating the Helm chart currently requires additional changes in the helm-chart repo.

Suggestion: Move the chart back to this repo and automate the release process.

This would have three direct consequences:

• The versioning schema of the chart would change to follow that of Dex
• Breaking changes would not be allowed (or would have to be limited) until we tag Dex 3.x (it may not be that big of an issue
• We would have to switch from Helm chart repos to OCI artifacts as the distribution mechanism