[Serve] User custom class name for replica class

[simon-mo]

Why are these changes needed?

The actor class name for replica wrappers are long and hard to read. This PR uses type to create the wrapper class so the class name is more informative. This behavior is also compatible with previous approach using __name__. But previous approach only affect the proctitle of worker process; while this approach change both proctitle and how Ray recognize the class name.

This make Serve looks way better through observability api.

## before
(base) ➜  ray list actors
---
-   actor_id: 36eaf5c0b16cacee19eed7b101000000
    class_name: ServeController
    name: SERVE_CONTROLLER_ACTOR
    pid: 43088
    state: ALIVE
-   actor_id: a68ec943681d5305aec6c24201000000
    class_name: create_replica_wrapper.<locals>.RayServeWrappedReplica
    name: SERVE_REPLICA::b#ZVpdBy
    pid: 43104
    state: ALIVE
-   actor_id: e4f7395a757050e6f49ce2df01000000
    class_name: HTTPProxyActor
    name: SERVE_CONTROLLER_ACTOR:SERVE_PROXY_ACTOR-node:127.0.0.1-0
    pid: 43098
    state: ALIVE

## after
(base) ➜ ray list actors
---
-   actor_id: 341f10755762b5c428eb54ec01000000
    class_name: ServeController
    name: SERVE_CONTROLLER_ACTOR
    pid: 44665
    state: ALIVE
-   actor_id: 44d9d9286c8783862898e0da01000000
    class_name: ServeReplicaClass:b
    name: SERVE_REPLICA::b#souBqw
    pid: 44672
    state: ALIVE
-   actor_id: 56968306b7f8c2f79a56b6e701000000
    class_name: HTTPProxyActor
    name: SERVE_CONTROLLER_ACTOR:SERVE_PROXY_ACTOR-node:127.0.0.1-0
    pid: 44667
    state: ALIVE

Related issue number

None

Checks

• I've run scripts/format.sh to lint the changes in this PR.
• I've included any doc changes needed for https://docs.ray.io/en/master/.
• I've made sure the tests are passing. Note that there might be a few flaky tests, see the recent failures at https://flakey-tests.ray.io/
• Testing Strategy
  • Unit tests
  • Release tests
  • This PR is not tested :(

[rickyyx]

via GIPHY

[edoakes]

@simon-mo nice, I noticed this while using the actors API too, you beat me to it ;)

[rkooo567]

This is awesome :)!