feat: support SessionPersistence on GRPCRoute (currently HTTPRoute-only)

[MengjiaLiang]

Description:
Today Envoy Gateway honors the Gateway API SessionPersistence field only on HTTPRouteRule.

The equivalent translator for gRPC, processGRPCRouteRule , does not reference SessionPersistence at all.

Happy to drive a PR if maintainers are open to this — wanted to file the issue first to confirm scope and any concerns

[jukie]

Thanks. +1 on supporting this

[zhaohuabing]

+1

[github-actions]

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

[zirain]

@MengjiaLiang are you still working on this?

[github-actions]

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

[MengjiaLiang]

Hi @zirain , sorry for the delayed response. I was distracted by a few other things.
Will raise a PR for it in the next week or 2. (Have some internal process needs to go through)