Porting 'ansi' command from nushell to engine-q (#494)

* Porting 'ansi' command from nushell to engine-q

* Added StrCollect to example_test.rs to allow example tests to run

* Run 'cargo fmt' to fix formatting

* Update command.rs

* Update command.rs

* Update command.rs

* Added a category

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

crates/nu-command/src/default_context.rs

@@ -129,6 +129,7 @@ pub fn create_default_context() -> EngineState {
             StrSubstring,
             StrTrim,
             StrUpcase,
+            Ansi
         };
 
         // FileSystem