Split HTTP and TCP/UDP access log format in EnvoyProxy

*Description*:

HTTP and TCP/UDP don't have same command operators, `REQ` and `RESP` operators only in HTTP is important for observability. If operators only in HTTP is configured for TCP/UDP, `-` will be placed in related access log operator.

If user wants to deploy HTTP and TCP/UDP listeners under same GatewayClass with `mergeGateways` enabled, user can't attach EnvoyProxy to Gateway to let different Gateway use their own access log format, then TCP/UDP will have massive `-` in access log, it's unnecessary overhead and produce useless info to access log.

As a workaround, user can choose to split HTTP and TCP/UDP to different GatewayClass with their own necessary access log format.

Maybe we can consider allow user to configure access log format for HTTP and TCP/UDP separately in EnvoyProxy.

[optional *Relevant Links*:]

> https://gateway.envoyproxy.io/v1.0.2/api/extension_types/#proxyaccesslogsetting
> https://www.envoyproxy.io/docs/envoy/latest/configuration/observability/access_log/usage#command-operators