apisix-ingress-controller chart missing podLabels support

Chart version: apisix-ingress-controller v1.2.0

The deployment template renders pod labels exclusively via selectorLabels:

```
template:
metadata:
labels:
{{- include "apisix-ingress-controller-manager.selectorLabels" . | nindent 8 }}

```
There is no podLabels (or equivalent) value that gets merged into the pod template labels, making it impossible to add custom labels to pods for observability, scheduling, or policy purposes.

The apisix chart in the same repo supports this via `service.labelsOverride`. A straightforward fix for the ingress controller would be a deployment.podLabels value merged alongside
selectorLabels:

```
labels:
{{- include "apisix-ingress-controller-manager.selectorLabels" . | nindent 8 }}
{{- with .Values.deployment.podLabels }}
{{- toYaml . | nindent 8 }}
{{- end }}
```

Note: `deployment.podAnnotations` is already supported. The missing piece is labels only.

Start with the ingress-controller deployment template and its values alongside the existing deployment.podAnnotations support; compare the APISIX chart's service.labelsOverride behavior. Verify chart rendering with deployment.podLabels set and confirm selector labels remain while custom pod labels appear in the pod template.

Written by the indexing model from the issue text.