elif condition in routing

[lgogolin]

What would you like to see!

Add the functionality of elif condition in Routes

This would allow to trigger multiple escalation chains and notify multiple slack channels.

It's very common that some alerts would notify more than one team.
Also it's currently impossible to create more complex escalation policies that would include multiple time ranges for example:

1. Notification for schedule
2. Wait 5 min
3. Continue escalation if time 17:00 -> 8:00
4. Continue escaltion if time 8:00 -> 17:00

Product Area

Alert Flow & Configuration

Anything else to add?

No response

[github-actions]

The current version of Grafana OnCall, at the time this issue was opened, is v1.14.1. If your issue pertains to an older version of Grafana OnCall, please be sure to list it in the PR description. Thank you 😄!