feat: add C ndarray interface and refactor implementation for stats/base/dmeanvar

[gururaj1512]

---

type: pre_commit_static_analysis_report
description: Results of running static analysis checks when committing changes. report:

• task: lint_filenames status: passed
• task: lint_editorconfig status: passed
• task: lint_markdown status: passed
• task: lint_package_json status: na
• task: lint_repl_help status: passed
• task: lint_javascript_src status: passed
• task: lint_javascript_cli status: na
• task: lint_javascript_examples status: passed
• task: lint_javascript_tests status: passed
• task: lint_javascript_benchmarks status: passed
• task: lint_python status: na
• task: lint_r status: na
• task: lint_c_src status: missing_dependencies
• task: lint_c_examples status: missing_dependencies
• task: lint_c_benchmarks status: na
• task: lint_c_tests_fixtures status: na
• task: lint_shell status: na
• task: lint_typescript_declarations status: na
• task: lint_typescript_tests status: na
• task: lint_license_headers status: passed ---

Resolves None

Description

What is the purpose of this pull request?

This pull request:

• adds C ndarray interface for stats/base/dmeanvar
• refactors JavaScript implementation
• refactors tests, docs, benchmarks and examples.

Related Issues

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This pull request:

• None

Questions

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No.

Other

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No.

Checklist

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• Read, understood, and followed the contributing guidelines.

---

@stdlib-js/reviewers

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
stats/base/dmeanvar	$\color{green}370/370$ $\color{green}+100.00\%$	$\color{green}15/15$ $\color{green}+100.00\%$	$\color{green}4/4$ $\color{green}+100.00\%$	$\color{green}370/370$ $\color{green}+100.00\%$

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

[kgryte]

LGTM