Add support for user-defined labels on pulp-web-svc

[ismaildem]

Is your feature request related to a problem? Please describe.
The Pulp Operator currently allows user-defined annotations (service_annotations) on the pulp-web-svc Kubernetes Service, but does not support user-defined labels.
This is a limitation for environments where Services must be selected or controlled using labels, for example when integrating with external controllers (i.e. loadbalancer), which relies on labels.

Describe the solution you'd like
Add support for user-defined labels on the pulp-web-svc Service, configurable via the Pulp custom resource similar to the existing annotation support.

Describe alternatives you've considered
Manually patching the pulp-web-svc Service to add labels, which is overwritten by the operator during reconciliation.