[RFC]: add `fs/stat`

### Description

This RFC proposes adding the package `@stdlib/fs/stat` for inspecting details of files asynchronously and synchronously.

```javascript
var stat = require( '@stdlib/fs/stat' );
var statSync = require( '@stdlib/fs/stat' ).sync;
```

### Related Issues

None.

### 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:`.