nu-cli refactor moving commands into their own crate nu-command (#2910)

* move commands, futures.rs, script.rs, utils

* move over maybe_print_errors

* add nu_command crate references to nu_cli

* in commands.rs open up to pub mod from pub(crate)

* nu-cli, nu-command, and nu tests are now passing

* cargo fmt

* clean up nu-cli/src/prelude.rs

* code cleanup

* for some reason lex.rs was not formatted, may be causing my error

* remove mod completion from lib.rs which was not being used along with quickcheck macros

* add in allow unused imports

* comment out one failing external test; comment out one failing internal test

* revert commenting out failing tests; something else might be going on; someone with a windows machine should check and see what is going on with these failing windows tests

* Update Cargo.toml

Extend the optional features to nu-command

Co-authored-by: Jonathan Turner <jonathandturner@users.noreply.github.com>

crates/nu-parser/src/lex.rs

@@ -37,21 +37,11 @@ pub enum TokenContents {
 impl fmt::Display for TokenContents {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
-            TokenContents::Baseline(base) => {
-                write!(f, "{}", base)
-            }
-            TokenContents::Comment(comm) => {
-                write!(f, "#{}", comm)
-            }
-            TokenContents::Pipe => {
-                write!(f, "|")
-            }
-            TokenContents::Semicolon => {
-                write!(f, ";")
-            }
-            TokenContents::EOL => {
-                write!(f, "\\n")
-            }
+            TokenContents::Baseline(base) => write!(f, "{}", base),
+            TokenContents::Comment(comm) => write!(f, "#{}", comm),
+            TokenContents::Pipe => write!(f, "|"),
+            TokenContents::Semicolon => write!(f, ";"),
+            TokenContents::EOL => write!(f, "\\n"),
         }
     }
 }