Support ZREVRANK: Added the optional WITHSCORE argument.

[chayim]

Documented here.

[SoulPancake]

I'd like to work on this @chayim

[SoulPancake]

In the documentation for this and ZRANK both ( #2527 ) the examples for the withscore arg shows an error,
is that supposed to be updated? Should we raise it somewhere else?

[SoulPancake]

I found it raised redis/redis-doc#2354
here
Trying to find clarity on the response and then would write tests for the new cmd with optional arg.

[SoulPancake]

@monkey92t For this and #2527
Should we introduce a new command with the withScore param
Or should we replace the existing one with something like

type ZRankCmd struct {
	baseCmd

	member   string
	withScore bool
	val      []interface{}
}

And then handle it accordingly?

[SoulPancake]

My vote would be to add a separate ZRankWithScore Command
What are your thoughts? @monkey92t @chayim