Support outbound call within Envoy's cluster from Golang filter

*Title*: *Support outbound call within Envoy's cluster from Golang filter*

*Description*:
Currently, when there is a need to make outbound calls within Golang filter, the filter will handle by itself which is unfortunate that the current implementation cannot utilize Envoy's full capabilities, such as circuit-breaking, retry mechanisms, locality-aware routing, and other advanced features.

In comparison to the Lua filter, which has been supported through [`httpcall`](https://www.envoyproxy.io/docs/envoy/latest/configuration/http/http_filters/lua_filter#httpcall).

[optional *Relevant Links*:]
>Any extra documentation required to understand the issue.