feat: add math/base/special/roundnf implementation

[NishchayRajput]

Ref: #649.

Description

What is the purpose of this pull request?

This pull request:

• Implementation of math/base/special/roundnf

Related Issues

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This pull request:

• Ref: [RFC]: Add C implementations to base special math functions (tracking issue) #649

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No.

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• Read, understood, and followed the contributing guidelines.

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@stdlib-js/reviewers

[ShabiShett07]

/stdlib update-copyright-years

[ShabiShett07]

I think this PR also has a pre requisite which is powf. Maybe it needs to be merged first till then it can be operated using pow

[Planeshifter]

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