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/reduce.rs

@@ -0,0 +1,107 @@
+use nu_test_support::{nu, pipeline};
+
+#[test]
+fn reduce_table_column() {
+    let actual = nu!(
+        cwd: ".", pipeline(
+        r#"
+        echo "[{month:2,total:30}, {month:3,total:10}, {month:4,total:3}, {month:5,total:60}]"
+        | from json
+        | get total
+        | reduce -f 20 { = $it + $( math eval `{{$acc}}^1.05` )}
+        | str from -d 1
+        "#
+        )
+    );
+
+    assert_eq!(actual.out, "180.6");
+
+    let actual = nu!(
+        cwd: ".", pipeline(
+        r#"
+        echo "[{month:2,total:30}, {month:3,total:10}, {month:4,total:3}, {month:5,total:60}]"
+        | from json
+        | reduce -f 20 { = $it.total + $( math eval `{{$acc}}^1.05` )}
+        | str from -d 1
+        "#
+        )
+    );
+
+    assert_eq!(actual.out, "180.6");
+}
+
+#[test]
+fn reduce_rows_example() {
+    let actual = nu!(
+        cwd: ".", pipeline(
+        r#"
+        echo a,b 1,2 3,4
+        | split column ,
+        | headers
+        | reduce -f 1.6 { = $acc * $(echo $it.a | str to-int) + $(echo $it.b | str to-int) }
+        "#
+        )
+    );
+
+    assert_eq!(actual.out, "14.8");
+}
+
+#[test]
+fn reduce_numbered_example() {
+    let actual = nu!(
+        cwd: ".", pipeline(
+        r#"
+        echo one longest three bar
+        | reduce -n { if $(echo $it.item | str length) > $(echo $acc.item | str length) {echo $it} {echo $acc}}
+        | get index
+        "#
+        )
+    );
+
+    assert_eq!(actual.out, "1");
+}
+
+#[test]
+fn folding_with_tables() {
+    let actual = nu!(
+        cwd: ".", pipeline(
+        r#"
+        echo [10 20 30 40]
+        | reduce -f [] {
+            with-env [value $it] {
+              echo $acc | append $(= 10 * $(= $nu.env.value | str to-int))
+            }
+          }
+        | math sum
+        "#
+        )
+    );
+
+    assert_eq!(actual.out, "1000");
+}
+
+#[test]
+fn error_reduce_fold_type_mismatch() {
+    let actual = nu!(
+        cwd: ".", pipeline(
+        r#"
+        echo a b c | reduce -f 0 { = $acc + $it }
+        "#
+        )
+    );
+
+    assert!(actual.err.contains("Coercion"));
+}
+
+#[test]
+fn error_reduce_empty() {
+    let actual = nu!(
+        cwd: ".", pipeline(
+        r#"
+        reduce { = $acc + $it }
+        "#
+        )
+    );
+
+    assert!(actual.err.contains("needs input"));
+}