Remove CheckConfig.Spec.Handlers field

[calebhailey]

Feature Suggestion

Remove the CheckConfig.Spec.Handlers field in favor of the new CheckConfig.Spec.Pipelines field.

Possible Implementation

Version bump the CheckConfig resource to core/v3.CheckConfig. We could potentially offer some backwards compatibility here:

• Auto migrate existing CheckConfig resources (convert CheckConfig.Spec.Handlers to CheckConfig.Spec.Pipelines)
• Maintain support for processing core/v2.CheckConfig resources and auto-converting them to core/v3.CheckConfig resources (but log a warning message?)

Context

Pipelines are the future!

[fguimond]

Deprecate handler sets and motivate users to move to core/v3.CheckConfig. Needs move to core/v3.Event referencing core/v3.CheckConfig. Requires rebuilding every integration.