feat: support adding annotations to Deployment

[mstefany]

Allowing to add annotations for Deployment object of apisix-ingress-controller makes usage of 3rd party tools like reloader possible, e.g.:

apiVersion: apps/v1
kind: Deployment
metadata:
  annotations:
    meta.helm.sh/release-name: ingress-apisix
    meta.helm.sh/release-namespace: ingress-apisix
    reloader.stakater.com/auto: "true"
[...]

Use case: We are delivering admin key to Kubernetes using external-secrets-operator and then passing into apisix via environment variable, and we want ingress controllers to be automatically reloaded when update of secret happens. For this purpose, we need to be able to add reloader annotation to the deployment object.