Refactor operator Package

[IfSentient]

The operator package needs some refactoring, which will introduce breaking changes that had been held off until the v0.24 LTS release. These changes include:

• Move from consuming chan <- struct{} as signal channels to context.Context, and propagate the context into children [operator] Use contexts instead of channels for Run methods #484
• Use app.Runnable (or a similar interface) in operator and controller logic (this follows from consuming context.Context)
• Allow operator.InformerController to manage its individual informers better, so they can be added and removed dynamically, while running. Some initial work has already been done here.
• Propagate context from operator.InformerController into watchers/reconcilers when event methods are called [operator] Use contexts instead of channels for Run methods #484
• Clean up New functions