feat: add math/base/special/roundf

[gunjjoshi]

Description

What is the purpose of this pull request?

This pull request:

• adds math/base/special/roundf, which would be the single-precision equivalent for math/base/special/round.

float stdlib_base_roundf( const float x );

Related Issues

Does this pull request have any related issues?

This pull request:

• resolves a part of [RFC]: Add C implementations to base special math functions (tracking issue) #649.

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.

• I have emulated the logic of the C implementation of math/base/special/round in the javascript implementation of roundf as well, rather than using a built-in function. I believe it would be great if we update math/base/special/round too, thus avoiding the built-in function.
• I have used 8388608.0 as we're dealing with float, rather than 4503599627370496.0 as the extreme value.
• Coverage report:

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

[Planeshifter]

LGTM!