Support for targeting sections (Gateway listener/Route Rule) in BackendTrafficPolicy

[kkk777-7]

Description:

Describe the desired behavior, what scenario it enables and how it
would be used.

This is an Issue that helps you keep track of multiple, scattered issues.
Relates to #2054 & #4085

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Any extra documentation required to understand the issue.

[github-actions]

This issue has been automatically marked as stale because it has not had activity in the last 30 days.