[RFC]: improve type declarations for `@stdlib/ndarray/array`

### Description

This RFC proposes improving the TypeScript type declarations for `@stdlib/ndarray/array`. Currently, type declarations do not account for `dtype` information.

Ideally, we'd improve declarations such that

- based on a provided `dtype` option value, we return an `ndarray` of the corresponding type (e.g., if `dtype = 'float64'`, then return a `float64ndarray`, etc).
- when not provided a `dtype` option value, we use the `buffer` argument/option to infer a corresponding output `ndarray` dtype.

Supporting the above is likely to require extensive use of function overloads in a manner to what we've done elsewhere in the project when a dtype can effect output results.

### Related Issues

No.

### 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:`.