Remove actor handle IDs (#5889)

* Remove actor handle ID from main ActorHandle constructor

* Set the actor caller ID when calling submit task instead of in the actor handle

* Remove ActorHandle::Fork, remove actor handle ID from protobuf

* Make inner actor handle const, remove new_actor_handles

* Move caller ID into the common task spec, start refactoring raylet

* Some fixes for forking actor handles

* Store ActorHandle state in CoreWorker, only expose actor ID to Python

* Remove some unused fields

* lint

* doc

* fix merge

* Remove ActorHandleID from python/cpp

* doc

* Fix core worker test

* Move actor table subscription to CoreWorker, reset actor handles on actor failure

* lint

* Remove GCS client from direct actor

* fix tests

* Fix

* Fix tests for raylet codepath

* Fix local mode

* Fix multithreaded test

* Fix AsyncSubscribe issue...

* doc

* fix serve

* Revert bazel

python/ray/includes/unique_ids.pxi

@@ -11,7 +11,6 @@ import os
 from ray.includes.unique_ids cimport (
     CActorCheckpointID,
     CActorClassID,
-    CActorHandleID,
     CActorID,
     CClientID,
     CConfigID,
@@ -343,16 +342,6 @@ cdef class ActorID(BaseID):
         return self.data.Hash()
 
 
-cdef class ActorHandleID(UniqueID):
-
-    def __init__(self, id):
-        check_id(id)
-        self.data = CActorHandleID.FromBinary(<c_string>id)
-
-    cdef CActorHandleID native(self):
-        return <CActorHandleID>self.data
-
-
 cdef class ActorCheckpointID(UniqueID):
 
     def __init__(self, id):
@@ -385,7 +374,6 @@ cdef class ActorClassID(UniqueID):
 _ID_TYPES = [
     ActorCheckpointID,
     ActorClassID,
-    ActorHandleID,
     ActorID,
     ClientID,
     JobID,