Enable overriding of ingress api version for systems where detection doesn't work (#252)

fixes #251

The rendering is a bit more programatic but the result is the same if you don't have an override.  This makes the code a little easier at the end of the template, and slightly less easier to read at the beginning, which I think is a valid tradeoff.

Co-authored-by: Martyn Ranyard <m@rtyn.berlin>
Reviewed-on: https://gitea.com/gitea/helm-chart/pulls/252
Reviewed-by: justusbunsi <justusbunsi@noreply.gitea.io>
Reviewed-by: luhahn <luhahn@noreply.gitea.io>
Co-authored-by: iMartyn <imartyn@noreply.gitea.io>
Co-committed-by: iMartyn <imartyn@noreply.gitea.io>

values.yaml

@@ -78,6 +78,9 @@ ingress:
   #  - secretName: chart-example-tls
   #    hosts:
   #      - git.example.com
+  # Mostly for argocd or any other CI that uses `helm template | kubectl apply` or similar
+  # If helm doesn't correctly detect your ingress API version you can set it here.
+  # apiVersion: networking.k8s.io/v1
 
 resources: {}
   # We usually recommend not to specify default resources and to leave this as a conscious