[NEW] Supports invoke RM_Call() on the replica node for read-only cmd

[jjz921024]

The problem/use-case that the feature addresses

I want to implement a module that exec read-only commands on the replica node. such as:

RedisModuleCallReply *reply = RedisModule_Call(ctx, "TYPE", "s", key);

But, the return value reply is always NULL.

[hwware]

Can you try the RedisModule_Call(ctx, "TYPE", "c", key); ？ I try this way works (BTW, i just set key as 1000, I am not sure how your key type)