Add support for overriding the resolved path for a given Module or Dist.

As per request [rt#95721 [Feature request] Add official way to override share resoluion](https://rt.cpan.org/Ticket/Display.html?id=95721)

This is the simplest approach I could think of that might be useful enough to be extensible.

The logic for `Dist` must go in `_dist_dir_new()` because it is directly called `_dist_file_new()` but `_dist_dir()` is not called anywhere in `_dist_file()`