[RFC]: move strided packages from `stats/base/*` to `stats/strided/*`

### Description

This RFC proposes moving strided array packages found in [`@stdlib/stats/base`](https://github.com/stdlib-js/stdlib/tree/1fa205cc4a6002a53be6fda15006749a0e18eeec/lib/node_modules/%40stdlib/stats/base) to a `@stdlib/strided` namespace. For example,

- `@stdlib/stats/base/dmeanli` => `@stdlib/stats/strided/dmeanli`
- `@stdlib/stats/base/svariancepn` => `@stdlib/stats/strided/svariancepn`

Currently, the stats/base namespace is a mixture of "base" functionality (namely, lower-level scalar dists kernels) and strided array interfaces. This RFC proposes moving the stats namespace to be more consistent with the `@stdlib/math/strided` and `@stdlib/random/strided` namespaces, where strided array APIs are found in a dedicated `strided` subnamespace.

### Related Issues

- https://github.com/stdlib-js/stdlib/issues/2261

### Questions

No.

### Other

The migration path would be as follows:

- copy strided array packages to a `stats/strided` sub-namespace.
- update all require paths using the `stats/base` strided packages.
- remove all strided packages from `stats/base`.

Note, however, that the migration process requires a very specific sequence of steps (i.e., commits). As such, this is **not** a good first issue.

### 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:`.