Error out when Select gets same row (#8200)

# Description
Fixes #8145, by disallowing any rows that are duplicated.

```
❯ ls | select 0 0
Error: 
  × Select only allows unique rows
   ╭─[entry #1:1:1]
 1 │ ls | select 0 0
   ·               ┬
   ·               ╰── duplicated row
   ╰────

```

# User-Facing Changes


# Tests + Formatting

Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- [X] `cargo fmt --all -- --check` to check standard code formatting
(`cargo fmt --all` applies these changes)
- [X] `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect` to check that you're using the standard code
style
- [X] `cargo test --workspace` to check that all tests pass

# After Submitting

If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.

---------

Co-authored-by: Reilly Wood <reilly.wood@icloud.com>

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

@@ -272,3 +272,15 @@ fn select_failed3() {
     assert!(actual.out.is_empty());
     assert!(actual.err.contains("cannot find column"));
 }
+
+#[test]
+fn select_failed4() {
+    let actual = nu!(
+        cwd: ".", pipeline(
+        r#"
+        [{a: 1 b: 10}, {a:2, b:11}] | select 0 0
+        "#
+    ));
+
+    assert!(actual.err.contains("Select can't get the same row twice"));
+}