Refactor first and last (#12478)

# Description

- Refactors `first` and `last` using `Vec::truncate` and `Vec::drain`.
- `std::mem::take` was also used to eliminate a few `Value` clones.
- The `NeedsPositiveValue` error now uses the span of the `rows`
argument instead of the call head span.
- `last` now errors on an empty stream to match `first` which does
error.
-  Made metadata preservation more consistent.

# User-Facing Changes
Breaking change: `last` now errors on an empty stream to match `first`
which does error.

crates/nu-command/tests/commands/default.rs

@@ -28,7 +28,7 @@ fn adds_row_data_if_column_missing() {
 
 #[test]
 fn default_after_empty_filter() {
-    let actual = nu!("[a b] | where $it == 'c' | last | default 'd'");
+    let actual = nu!("[a b] | where $it == 'c' | get -i 0 | default 'd'");
 
     assert_eq!(actual.out, "d");
 }

crates/nu-command/tests/commands/first.rs

@@ -51,7 +51,7 @@ fn gets_first_row_when_no_amount_given() {
 fn gets_first_row_as_list_when_amount_given() {
     let actual = nu!("[1, 2, 3] | first 1 | describe");
 
-    assert_eq!(actual.out, "list<int> (stream)");
+    assert_eq!(actual.out, "list<int>");
 }
 
 #[test]

crates/nu-command/tests/commands/last.rs

@@ -51,7 +51,7 @@ fn requests_more_rows_than_table_has() {
 fn gets_last_row_as_list_when_amount_given() {
     let actual = nu!("[1, 2, 3] | last 1 | describe");
 
-    assert_eq!(actual.out, "list<int> (stream)");
+    assert_eq!(actual.out, "list<int>");
 }
 
 #[test]