Move std::fs::file.remove to std::fs::path::Path.remove

[yorickpeterse]

Description

This module method is a bit of a remnant from when we had more module methods for file system operations. In the interest of being consistent and only having one way of doing things, this method should be move to Path.remove as an instance method.

While this seems a bit annoying, it helps keep path related logic in the Path type. This in turn means that if at some point we want to change it to not be backed by a String (#314), we keep all the changes contained to a single type.

Related work

No response