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-command/tests/commands/last.rs

@@ -0,0 +1,66 @@
+use nu_test_support::fs::Stub::EmptyFile;
+use nu_test_support::playground::Playground;
+use nu_test_support::{nu, pipeline};
+
+#[test]
+fn gets_the_last_row() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats",
+        "ls | sort-by name | last 1 | get name | str trim"
+    );
+
+    assert_eq!(actual.out, "utf16.ini");
+}
+
+#[test]
+fn gets_last_rows_by_amount() {
+    Playground::setup("last_test_1", |dirs, sandbox| {
+        sandbox.with_files(vec![
+            EmptyFile("los.txt"),
+            EmptyFile("tres.txt"),
+            EmptyFile("amigos.txt"),
+            EmptyFile("arepas.clu"),
+        ]);
+
+        let actual = nu!(
+            cwd: dirs.test(), pipeline(
+            r#"
+                ls
+                | last 3
+                | count
+            "#
+        ));
+
+        assert_eq!(actual.out, "3");
+    })
+}
+
+#[test]
+fn gets_last_row_when_no_amount_given() {
+    Playground::setup("last_test_2", |dirs, sandbox| {
+        sandbox.with_files(vec![EmptyFile("caballeros.txt"), EmptyFile("arepas.clu")]);
+
+        let actual = nu!(
+            cwd: dirs.test(), pipeline(
+            r#"
+                ls
+                | last
+                | count
+            "#
+        ));
+
+        assert_eq!(actual.out, "1");
+    })
+}
+
+#[test]
+fn requests_more_rows_than_table_has() {
+    let actual = nu!(
+        cwd: ".", pipeline(
+        r#"
+        date | last 50 | count
+        "#
+    ));
+
+    assert_eq!(actual.out, "1");
+}