Avoid taking unnecessary ownership of intermediates (#12740)

# Description

Judiciously try to avoid allocations/clone by changing the signature of
functions

- **Don't pass str by value unnecessarily if only read**
- **Don't require a vec in `Sandbox::with_files`**
- **Remove unnecessary string clone**
- **Fixup unnecessary borrow**
- **Use `&str` in shape color instead**
- **Vec -> Slice**
- **Elide string clone**
- **Elide `Path` clone**
- **Take &str to elide clone in tests**

# User-Facing Changes
None

# Tests + Formatting
This touches many tests purely in changing from owned to borrowed/static
data

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

@@ -17,7 +17,7 @@ export def expect [
 #[test]
 fn zips_two_tables() {
     Playground::setup("zip_test_1", |dirs, nu| {
-        nu.with_files(vec![FileWithContent(
+        nu.with_files(&[FileWithContent(
             "zip_test.nu",
             &format!("{ZIP_POWERED_TEST_ASSERTION_SCRIPT}\n"),
         )]);