Implement TestWork functionality for preserving working directories on failure

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

examples/test_runner.rs

@@ -8,8 +8,22 @@ fn main() {
         std::env::set_current_dir(manifest_dir).expect("Failed to change directory");
     }
 
-    // Run all tests in testdata directory
-    match testscript::run("testdata").execute() {
+    // Check for test directory from environment for test purposes
+    let test_dir = std::env::var("TESTSCRIPT_TEST_DIR").unwrap_or_else(|_| "testdata".to_string());
+    
+    // Check if preserve work should be enabled
+    let preserve_work = std::env::var("TESTSCRIPT_PRESERVE_WORK")
+        .map(|v| v == "true" || v == "1")
+        .unwrap_or(false);
+
+    // Run all tests in the specified directory
+    let mut builder = testscript::run(test_dir);
+    
+    if preserve_work {
+        builder = builder.preserve_work_on_failure(true);
+    }
+
+    match builder.execute() {
         Ok(()) => println!("All tests passed!"),
         Err(e) => {
             eprintln!("Test failed: {}", e);