[Infer] Serving example w/ ray-serve (multiple GPU case) (#4841)

* fix imports

* add ray-serve with Colossal-Infer tp

* trivial: send requests script

* add README

* fix worker port

* fix readme

* use app builder and autoscaling

* trivial: input args

* clean code; revise readme

* testci (skip example test)

* use auto model/tokenizer

* revert imports fix (fixed in other PRs)