add PUT/PATCH alert group internal API endpoints

[joeyorlando]

What this PR does

• Add PUT/PATCH alert group internal API endpoints. Will be consumed by the Grafana Incident API to update grafana_incident_id.
  • TODO: figure out how we will handle authnz here (we're currently talking with Identity Access team to possibly use the Cloud Auth API)
• Update the grafana_incident_id column to be a JSON column (so that we can support storing >= 1 Incident ID for a given alert group)
• Allow filtering alert groups by grafana_incident_id
• Update AlertGroup.declare_incident_link to include ID

Checklist

• Unit, integration, and e2e (if applicable) tests updated
• Documentation added (or pr:no public docs PR label added if not required)
• Added the relevant release notes label (see labels prefixed w/ release:). These labels dictate how your PR will
  show up in the autogenerated release notes.

[robert-northmind]

LGTM,
but.. 😄 I am no python or django developer but I think it looks good.
thanks @joeyorlando for driving this.

[github-actions]

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