feat: Add accept-images parameter to whitelist images

[vdombrovski]

This PR adds a new parameter called --accept-images, which behaves much like the --ignore-images parameter, except it provides a way to specify a whitelist of image regexes to rewrite. This check is done after ignore-images, so one can still specify a blacklist.

Use case:

• We want to cache public images from certain repos to optimize traffic and performance, without exposing private images. We understand that KEP 2535 will solve this issue in term, but it will only enter alpha stage in v1.32
• The current --ignore-images parameter doesn't do it for us, because Golang's regexp engine doesn't support negative lookaheads (meaning we can't make a whitelist out of this blacklist)
• We have added the --accept-images parameter, which, when it's not empty, will only rewrite images that match regexes (also integrated into the Helm chart)

Example usage (Helm values file):

controllers:
  webhook:
    acceptedImages:
    - "^gcr\\.io/.*"
    - "^ghcr\\.io/.*"
    - "^docker\\.io/.*"
    - "^registry\\.k8s\\.io.*"

This will cache only images coming from known public repos (provided image names are prefixed with the repo, but that's a compromise we are willing to accept).