feat: add stats/incr/nancv

[jalajk3004]

Resolves #5555

Description

What is the purpose of this pull request?

This pull request:

• adds a package nancv, which works like cv in which it calculates cv incrementally ignoring NaN values

Related Issues

Does this pull request have any related issues?

This pull request:

• resolves [RFC]: add stats/incr/nancv #5555

Questions

Any questions for reviewers of this pull request?

No.

Other

Any other information relevant to this pull request? This may include screenshots, references, and/or implementation notes.

No.

Checklist

Please ensure the following tasks are completed before submitting this pull request.

• Read, understood, and followed the contributing guidelines.

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@stdlib-js/reviewers

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
stats/incr/nancv	$\color{green}133/133$ $\color{green}+100.00\%$	$\color{green}8/8$ $\color{green}+100.00\%$	$\color{green}2/2$ $\color{green}+100.00\%$	$\color{green}133/133$ $\color{green}+100.00\%$

The above coverage report was generated for the changes in this PR.

[0PrashantYadav0]

@jalajk3004 Your header files for README.md file is creating lint error here. Do make sure to configure editconfig file properly. Few require statement need to be in order.

[kgryte]

All lint errors need to be resolved before this PR can be reviewed.

[jalajk3004]

All lint errors are resolved, you can review this PR