Move pingsource to v1beta1 umbrella issue

[lionelvillard]

Problem
We need to promote PingSource to v1beta1.

• v1beta1 types with UTs
• add new version to CRD
• defaulting and conversion webhook
• Update docs and examples (most in knative/docs)
• Update e2e tests to use v1beta1
• Migrate reconciler to v1beta1 with UTs
• Make v1beta the storage version

[lionelvillard]

Reposting here for extra visibility.

PingSource v1alphaX already supports timezone via CRON_TZ (or TZ) in the schedule. Maybe that's good enough and all what we need to do is updating the documentation.

I think I would still prefer to make it explicit in the spec. Before doing that I'd like to gather people feedback.

@n3wscott @nachocano @vaikas WDYT?

[n3wscott]

adding timezones will make it incompatible with a K8s CronJob?

[lionelvillard]

yes: kubernetes/kubernetes#47202

[lionelvillard]

CronJobber uses a field: https://github.com/hiddeco/cronjobber