Expose more Command create arguments

[liuchong]

Motivation:

Expose more Command create arguments to let user create custom command.

Or further, do you think we should a this? Please:

  static Command create(String command, int arity, Boolean readOnly, boolean pubsub, boolean needGetKeys, KeyLocator... keyLocators) {
    return new CommandImpl(command, arity, readOnly, pubsub, needGetKeys, keyLocators);
  }

In this case, maybe we should change package io.vertx.redis.client.impl.keys to io.vertx.redis.client.keys.

[pmlopes]

The key locator was previously and internal implementation detail. It was not correct according to redis. It now follows redis and still it's an internal implementation detail.

Which use case are you trying to do that would require this to be public?

[liuchong]

Ok, thanks for the explanation about the key locator. But how about the other arguments, the command, arity, readOnly and others...?
Before the commit 8d45692 in #328, I implemented something like that for the RedisBloom commands, use the function Command.create, only the bloom commands so I did not make a pull request here.
Although I don't need it now, because the commands are build-in supported now. But as we know there are many modules and one can also create new modules. Will the other arguments need to be public when we create new command with vertx-redis-client?