feat: add grafana v10 AlertRule support

[desmaraisp]

What does this do?

Grafana v10 has a slightly different format for alert rules, so the v9 version of the class cannot be used without overriding the to_json_data method. The PR implements the modified rendering that should work for grafana v10 alerts

Why is it a good idea?

Supporting v10 will help keeping the library relevant in the short term while cog matures. Once cog become mature enough, it might be an interesting option, but for now manual code changes are still the best way to go forward

Context

See #627

Questions

[lexi-k]

Hi, would it be possible to merge this please? We would also appreciate this change, although it hard to make the change ourselves, having it right in the "main" library would not trigger our "OCDs" as much ;-)

[pawel-biegun-sq3]

Hi @amotl, would it be possible to merge this? It looks like an essential improvement to support V10 dashboards.

[amotl]

Hi Pawel. I am not a member of the grafanalib project, so I can't help you here. Apologies.

[garett-eiq]

@JamesGibo any chance this might get merged soon? I'd be glad to help out in some way