feat(deployment)!: move dnsConfig to deployment.dnsConfig

`dnsConfig` was a top-level value although it exclusively configures the pod spec of the Gitea Deployment. With
`affinity` and `env` already moved into the `deployment` dict, keeping `dnsConfig` at the root level leaves the
Deployment configuration split across two places and makes it harder to see which values end up in the rendered
pod spec.

Moving it into the `deployment` dict continues the consolidation of Deployment-scoped values and keeps the
values structure predictable for the remaining pod-level settings.

A deprecation check is added so that existing installations fail fast with an actionable error message. Without
it, a custom DNS configuration would be dropped silently, which typically surfaces much later as unexplained
name resolution failures inside the Gitea pod.

BREAKING CHANGE: `dnsConfig` no longer exists. Use `deployment.dnsConfig` instead. Installations that still set
`dnsConfig` will fail unless `checkDeprecation` is set to `false`.

Co-authored-by: Copilot <copilot@github.com>

values.yaml

@@ -322,9 +322,6 @@ tolerations: []
 ## @param topologySpreadConstraints TopologySpreadConstraints for the deployment
 topologySpreadConstraints: []
 
-## @param dnsConfig dnsConfig for the deployment
-dnsConfig: {}
-
 ## @param priorityClassName priorityClassName for the deployment
 priorityClassName: ""
 
@@ -357,6 +354,17 @@ deployment:
     #         values:
     #         - amd64
 
+  ## @param deployment.dnsConfig dnsConfig of the Gitea deployment.
+  dnsConfig: {}
+    # nameservers:
+    # - 192.0.2.1 # this is an example
+    # searches:
+    # - ns1.svc.cluster-domain.example
+    # - my.dns.search.suffix
+    # options:
+    # - name: ndots
+    #   value: "2"
+    # - name: edns0
 
   gitea:
     ## @param deployment.gitea.env Additional environment variables to pass to the gitea container.