Add Path commands (#280)

* Add Path command

* Add `path basename`

* Refactor operate into `mod`

* Add `path dirname`

* Add `path exists`

* Add `path expand`

* Remove Arc wrapper for args

* Add `path type`

* Add `path relative`

* Add `path parse`

* Add `path split`

* Add `path join`

* Fix errors after rebase

* Convert to Path in `operate`

* Fix table behavior in `path join`

* Use conditional import in `path parse`

* Fix missing cases for `path join`

* Update default_context.rs

* clippy

* Fix tests

* Fix tests

Co-authored-by: JT <547158+jntrnr@users.noreply.github.com>
Co-authored-by: JT <jonathan.d.turner@gmail.com>

crates/nu-command/src/formats/to/md.rs

@@ -430,7 +430,7 @@ mod tests {
         );
 
         assert_eq!(
-            table(value.clone().into_pipeline_data(), true, &Config::default()),
+            table(value.into_pipeline_data(), true, &Config::default()),
             one(r#"
             | country     |
             | ----------- |