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/database/into_sqlite.rs

@@ -304,7 +304,7 @@ fn into_sqlite_big_insert() {
 
         let nuon_path = dirs.test().join(NUON_FILE_NAME);
 
-        playground.with_files(vec![Stub::EmptyFile(&nuon_path.to_string_lossy())]);
+        playground.with_files(&[Stub::EmptyFile(&nuon_path.to_string_lossy())]);
 
         let mut expected_rows = Vec::new();
         let mut nuon_file = std::fs::OpenOptions::new()