feat: add plot/vega/base/assert/is-format-type

[Sachinn-64]

Resolves None.

Description

What is the purpose of this pull request?

This pull request:

• feat: add plot/vega/base/assert/is-format-type

Related Issues

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This pull request has the following related issues:

• None

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Other

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Checklist

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• Read, understood, and followed the contributing guidelines.

AI Assistance

When authoring the changes proposed in this PR, did you use any kind of AI assistance?

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{{TODO: add disclosure if applicable}}

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@stdlib-js/reviewers

[Sachinn-64]

/stdlib update-copyright-years

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
plot/vega/base/assert/is-format-type	$\color{green}104/104$ $\color{green}+100.00%$	$\color{green}2/2$ $\color{green}+100.00%$	$\color{green}0/0$ $\color{green}+100.00%$	$\color{green}104/104$ $\color{green}+100.00%$

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