[RFC]: Add anglit distribution implementation

### Description

This RFC proposes to add an implementation of the anglit probability distribution to stdlib, following existing continuous distribution patterns.

The anglit distribution has support on [-π/4, π/4] with PDF cos(2x), and is available in SciPy as scipy.stats.anglit.

References:
1. SciPy – https://docs.scipy.org/doc/scipy/reference/generated/scipy.stats.anglit.html

### Related Issues

Related issues # , # , and # .

### 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:`.