Modules: expose real client on conn events.
Modules: expose real client on conn events.

When REDISMODULE_EVENT_CLIENT_CHANGE events are delivered, modules may
want to mutate the client state (e.g. perform authentication).

This change links the module context with the real client rather than a
fake client for these events.

JackieXie168/redis,JackieXie168/redis,JackieXie168/redis,JackieXie168/redis