#1126 Adding support for command ZRANK

[SyedMa3]

1. Adding implementation of ZRANK command.
2. Adding Unit test, Integration tests and benchmark.

Closes: #1126

For Reviewer's Checklist for Migration label PR/Issues

• [x] moved code from eval.go to store_eval.go
• [ ] updated cmd meta in eval, worker & server
• [x] moved tests from async to resp
• [x] added/updated tests in http and websocket
• [x] added/updated unit tests in eval folder
• [x] audited documentation and updated as per new standards
• [x] no changes in legacy async code / eval.go file
• [x] rebased with master
• [x] verified the code in local

[apoorvyadav1111]

Hi @SyedMa3, I will review your changes and share comments as I progress.

Thanks.

[apoorvyadav1111]

Hi, please update your websocket test as per latest master branch. Thanks