Verify the current resources by checking label and its value

[houshengbo]

Problem The function named deleteObsoleteResources can delete the resources by verifying if the the value matches the operand's version for the label eventing.knative.dev/release. Instead of deleting the obsolete resource on a release basis. Let's make it more general and intelligent.

Persona: This is for regular users of operator.

Exit Criteria Tests can be added to confirm that the resources have the label eventing.knative.dev/release, and the value matches the current operand version.

Time Estimate (optional): How many developer-days do you think this may take to resolve?

Additional context (optional) Add any other context about the feature request here.

[evankanderson]

This is a possible option; one challenge (which may not be too much of a problem here) is that it's hard to perform a label search across multiple Kinds.

For the operator case, this seems feasible by maintaining a list of all Kinds which have been previously used by Knative, which (ignoring downstream packaging) should allow finding the complete set of previous resources.