Refactor: added stats/incr/nanmmax

[thedeeppp]

Resolves #5584

Description

What is the purpose of this pull request?

This pull request:

• proposed @stdlib/stats/incr/nanmmax similar to @stdlib/stats/incr/mmax
• added test, benchmark and example files

Related Issues

Does this pull request have any related issues?

This pull request:

• resolves #5584

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.

• [x] Read, understood, and followed the contributing guidelines.

---

@stdlib-js/reviewers

[thedeeppp]

hey @kgryte please look at the changes as per asked and lmk if anything more requires

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
stats/incr/nanmmax	$\color{green}183/183$ $\color{green}+100.00\%$	$\color{red}23/24$ $\color{green}+95.83\%$	$\color{green}2/2$ $\color{green}+100.00\%$	$\color{green}183/183$ $\color{green}+100.00\%$

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