Make `Path` more consistent with `Array` for array types.

If a `Path` object is an array type, it should probably act more like the built-in `Array` class.
Here's what I'm thinking:
- Rename `each` to `forEach`
- Add a `length` property
- Add some/all of the `Array` methods, such as: `concat`, `every`, `find`, `reduce`, `reverse`, `slice`, `some`, `sort`, `splice`.

Start by locating the Path implementation and the handling for array-type Path objects. Compare the requested behavior with the built-in Array API and determine which methods are in scope; done means the agreed Array-like interface is implemented and covered by the relevant tests, though no test files are named in the issue.

Written by the indexing model from the issue text.