[RFC]: add `blas/base/csscal`

### Description

This RFC proposes adding the package `@stdlib/blas/base/csscal` for scaling a single-precision complex number by a real constant:
```c
void csscal(const int N, const float alpha, void *X, const int strideX);
```

### Related Issues

Related issues: #2039 (Tracker)

### Questions

No.

### Other

No.

### Checklist

- [X] I have read and understood the [Code of Conduct](https://github.com/stdlib-js/stdlib/blob/develop/CODE_OF_CONDUCT.md).
- [X] Searched for existing issues and pull requests.
- [X] The issue name begins with `RFC:`.

Start by reviewing the proposed csscal API and related tracker issue #2039. No implementation files, tests, or entry points are named, so identify the package structure and corresponding test conventions before proceeding; done means adding the proposed @stdlib/blas/base/csscal package with the stated interface.

Rédigé par le modèle d'indexation à partir du texte de l'issue.