.ops: expose grafana and kubernetes-dashboard behind oauth2-proxy with github provider

[BacLuc]

That we don't need kubectl to access these internal services. Can be used for the kibana from https://github.com/ecamp/ecamp3/pull/5039, or the kubernetes dashboard from https://github.com/ecamp/ecamp3/issues/4134

See for yourself at https://dev-grafana.ecamp3.ch/?orgId=1

Also add kubernetes-dashboard behind oauth-proxy

An access token can be generated with kubectl -n ops-dashboard create token kubernetes-dashboard-admin-user (I will move this text to the wiki once the PR is merged)

See at https://dev-kubernetes-dashboard.ecamp3.ch

closes #4134

[BacLuc]

Nice 🚀 How would we add a 2nd service (like kibana)? Would we need a 2nd deployment of this ops-dashboard? Or we could add a 2nd upstream config?

I didn't get oauth2-proxy to split traffic by host (by path it is no problem).

So i just added another oauth2-proxy instance. https://github.com/ecamp/ecamp3/pull/5073/commits/2cd83b7b2bf1100d735ec433570a178d6f26048e