Alertmanager just added a new incident.io receiver in their v0.29.0 version.

https://github.com/prometheus/alertmanager/releases/tag/v0.29.0

[FEATURE] Add incident.io notifier. prometheus/alertmanager#4372

It'd be great to have it supported in VMAlertmanagerConfig as we are using the VM operator to manage all our alert deployments and IIO for paging.

It should be implemented in the same way other receivers and keep tag format compatible with alertmanager.

(Similar to #1293)