refactor: refactor TCP IR

[aoledk]

Takes forward PR https://github.com/envoyproxy/gateway/pull/1976 and https://github.com/envoyproxy/gateway/pull/1798

Fixes: https://github.com/envoyproxy/gateway/issues/1635

[aoledk]

@arkodg I rebased your branch https://github.com/arkodg/gateway/tree/tls-ir-fix on the latest main branch, and adjusted TCPListener and TCPRoute fields according to BackendTrafficPolicy support for TCP Listener.

BTW, TCPListener.TCPKeepalive is not filled, because current main branch uses TCPKeepalive from BackendTrafficPolicy in both xDS TCP Listener and xDS Cluster. Which is not correct. We should use TCPKeepalive from ClientTrafficPolicy in xDS TCP Listener after https://github.com/envoyproxy/gateway/issues/3163 is implemented.

[arkodg]

thanks for taking the PR forward @aoledk ! will try to review this one soon before another round of merges making this refractor hard the keep alive issue is being tracked with https://github.com/envoyproxy/gateway/issues/3032 :)

[arkodg]

hey @aoledk there are some CI failures, running make generate and fixing the new format for the xds test should fix it

[aoledk]

hey @aoledk there are some CI failures, running make generate and fixing the new format for the xds test should fix it

I've run make generate and make testdata before committing.

And I've checked the detail of failed check, my branch is based on old main but PR is merge my branch into new main. I should merge the latest main into my branch to fix the CI failures.