[Feature] Mutating webhook for ingress annotations

Nobody has claimed this yet.

## Feature Request
A webhook or extension of the existing injector that will annotate ingresses automatically.

### What problem are you trying to solve?
Having to manually add annotations to every ingress object.

### How should the problem be solved?

I'm thinking a mutating webhook that will accept some configuration on install such that any ingress created within a namespace that is annotated for sidecar injection will get the necessary config annotations. A couple of things will be required:

* Some sort of configuration that specifies what type of controller, or some detection of controller type based on ingress annotations
* Possible that exclusion annotations might be necessary
* The ability to turn on/off the injector

What do you want to happen? Add any considered drawbacks.

### Any alternatives you've considered?

Is there another way to solve this problem that isn't as good a solution?

* An external mutating webhook controller

Review the existing injector and Kubernetes mutating-webhook path first; no specific file or test is named in the issue. A completed proposal should define install-time configuration, controller detection, exclusion and enable/disable behavior, with tests covering which ingress objects receive annotations.

Written by the indexing model from the issue text.