[RFC]: Add C implementation for `number/float32/base/signbit`

[Neerajpathak07]

Description

This RFC proposes

• adding C implementaions for @stdlib/number/float32/base/signbit which is a single-precision version of @stdlib/number/float64/base/signbit
• adding manifest.json file and other basic files.
• adding /src and /lib files.

Related Issues

Related issues #649

Questions

No.

Other

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Checklist

• I have read and understood the Code of Conduct.
• Searched for existing issues and pull requests.
• The issue name begins with RFC:.

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