* Add RM_ReplyWithErrorFormat that can support format
Reply with the error create from a printf format and arguments.
If the error code is already passed in the string 'fmt', the error
code provided is used, otherwise the string "-ERR " for the generic
error code is automatically added.
The usage is, for example:
RedisModule_ReplyWithErrorFormat(ctx, "An error: %s", "foo");
RedisModule_ReplyWithErrorFormat(ctx, "-WRONGTYPE Wrong Type: %s", "foo");
The function always returns REDISMODULE_OK.