refactor: use constant packages, `FI_F` for addon and style fixes in `math/base/special/ldexpf`

[gunjjoshi]

Description

What is the purpose of this pull request?

This pull request:

• addresses the changes suggested in the commit: https://github.com/stdlib-js/stdlib/commit/71c43cf5165749e2ce2647cb52d92f6c97f16959.
• uses FI_F in addon.c.
• Regarding the 100% test coverage, I tried different values, but there wasn't any pair of arguments for which the function reaches this block. So, I removed it in both implementations.
• contains some other style fixes.

Related Issues

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None.

Questions

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No.

Other

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• [x] Read, understood, and followed the contributing guidelines.

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