Improve "Did you mean?" suggestions (#6579)

* Copy lev_distance.rs from the rust compiler

* Minor changes to code from rust compiler

* "Did you mean" suggestions: test instrumented to generate markdown report

* Did you mean suggestions: delete test instrumentation

* Fix tests

* Fix test

`foo` has a genuine match: `for`

* Improve tests

crates/nu-protocol/src/lib.rs

@@ -5,6 +5,7 @@ pub mod engine;
 mod example;
 mod exportable;
 mod id;
+mod lev_distance;
 mod module;
 mod pipeline_data;
 mod shell_error;