Update both `Fs::trash_dir` and `Fs::trash_file` to now return the
location of the trashed directory or file, as well as adding the
`trash-rs` create dependency and updating the `RealFs` implementation
for these methods to simply leverage `trash::delete_with_info`.

* Add `fs::Fs::TrashedEntry` struct, which allows us to track the
  original file path and the new path in the OS' trash
* Update the `fs::Fs::trash_dir` and `fs::Fs::trash_file` signatures to
  now return `Result<TrashedEntry>` instead of `Result<()>`
* The `options` argument was removed because it was never used by
  implementations other than the default one, and with this change to
  the signature type, we no longer have a default implementation, so the
  `options` argument would no longer make sense
* Update `fs::RealFs::trash_dir` and `fs::RealFs::trash_file`
  implementations to simply delegate to `trash-rs` and convert the
  result to a `TrashedEntry`
* Add `fs::FakeFs::trash` so we can simulate the OS' trash during tests
  that touch the filesystem
* Add `fs::FakeFs::trash_file` implementation to leverage
  `fs::FakeFs::trash`
* Add `fs::FakeFs::trash_dir` implementation to leverage
  `fs::FakeFs::trash`