feat: Add support for incident.io Alert Channel

[tdeekens]

What problem does this feature solve?

incident.io is currently not a supported construct in the Checkly CLI. It's however a very powerful and often used product for incident management.

As a workaround one can use the fromId to reference an existing check as documented here.

It would be beneficial to allow having incident.io alert channels defined in code.

How would you implement this feature?

Adding another construct of type Alert Channel.

[tnolet]

@tdeekens thanks for reporting this. We are adding some effort on more webhook based 3rd party alert channels in the CLI in the next release. Keep an eye om the 5.x release coming soon.