Implement WorkdirRoot configuration feature

Co-authored-by: imjasonh <210737+imjasonh@users.noreply.github.com>

examples/test_workdir_root.rs

@@ -0,0 +1,37 @@
+use testscript_rs::testscript;
+use std::fs;
+use tempfile::TempDir;
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    println!("Testing workdir_root functionality...");
+    
+    // Create a custom root directory
+    let custom_root = "/tmp/test_workdir_root";
+    fs::create_dir_all(custom_root)?;
+    
+    // Create test data
+    let testdata = TempDir::new()?;
+    let testdata_path = testdata.path().join("testdata");
+    fs::create_dir(&testdata_path)?;
+    
+    let test_content = r#"exec echo "Testing workdir_root feature"
+stdout "Testing workdir_root feature"
+"#;
+    
+    fs::write(testdata_path.join("test.txt"), test_content)?;
+    
+    // Test with custom workdir root
+    println!("Running test with custom workdir root: {}", custom_root);
+    match testscript::run(testdata_path.to_string_lossy())
+        .workdir_root(custom_root)
+        .execute() {
+        Ok(()) => println!("✓ Test passed with custom workdir root!"),
+        Err(e) => {
+            eprintln!("✗ Test failed: {:?}", e);
+            return Err(e.into());
+        }
+    }
+    
+    println!("All tests passed! The workdir_root feature is working correctly.");
+    Ok(())
+}