Change of implementation of the domain to use ChallengeRequest DNSName

[ebrianne]

It tries to remove the domain value in the ClusterIssuer and to get the domain name based on the ChallengeRequest DNSNames that are provided when requesting a certificate.
It still needs to be able to handle multiple dns names inside the request (may need some changes upstream in https://github.com/ebrianne/duckdns-go)

Fixes #3

[ebrianne]

Tested with kind 1.20.2

helm install --wait --timeout 60s cert-manager-webhook-duckdns \                             ✘ INT at ⎈ kind-kind at  23:16:58
          --namespace cert-manager \
          --set duckdns.token='*****' \
          --set clusterIssuer.production.create=true \
          --set clusterIssuer.staging.create=true \
          --set clusterIssuer.email=***** \
          --set logLevel=6 --set image.tag=latest \
          ./deploy/cert-manager-webhook-duckdns

Request of certificate with two different wildcard domains

---
apiVersion: cert-manager.io/v1
kind: Certificate
metadata:
  name: services-***-duckdns-org
  namespace: services
spec:
  dnsNames:
  - '*.<domain1>.duckdns.org'
  - '*.<domain2>.duckdns.org'
  issuerRef:
    name: cert-manager-webhook-duckdns-production
    kind: ClusterIssuer
  secretName: services-****-duckdns-org-tls

Certificate issued perfectly

Events:
  Type    Reason     Age    From          Message
  ----    ------     ----   ----          -------
  Normal  Issuing    2m57s  cert-manager  Issuing certificate as Secret does not exist
  Normal  Generated  2m56s  cert-manager  Stored new private key in temporary Secret resource "services-****-duckdns-org-w9ggx"
  Normal  Requested  2m55s  cert-manager  Created new CertificateRequest resource "services-****-duckdns-org-q69s2"
  Normal  Issuing    102s   cert-manager  The certificate has been successfully issued

[ebrianne]

Fix #2 by downgrading to v1.19.0 go-client