Add a separate label for envoy or contour

[yangyy93]

What question do you have?:
The field PodAnnotations is now defined in the Spec of ContourDeployment, through which Annotations can be added to contour or envoy pods separately, but for Labels, there is no similar definition. I found that there was a PR (#5543) that implemented this function, but Closed due to merge of #5968.
Because of the merger of #5968, now we can either add annotations to envoy or contour separately, or add (same) annotations to both contour and envoy through gateway.infrastructure.annotation; I think it is a good idea to provide the ability to configure separate labels for envoy or contour for more flexible use.

[yangyy93]

@skriss @sunjayBhatia
have any opinions on this issue?

[github-actions]

The Contour project currently lacks enough contributors to adequately respond to all Issues.

This bot triages Issues according to the following rules:

• After 60d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, the Issue is closed

You can:

• Mark this Issue as fresh by commenting
• Close this Issue
• Offer to help out with triage

Please send feedback to the #contour channel in the Kubernetes Slack

[wilsonwu]

@skriss @sunjayBhatia any comments for this? We'd like to contribute it.