Add support for a "working-directory" parameter

This commit updates the tests to check that this works and also rewrites the
test script from Bash to Perl.

Co-authored-by: Dave Rolsky <autarch@urth.org>

test-project/subcrate/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "subcrate"
+version = "0.1.0"

test-project/subcrate/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "subcrate"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

test-project/subcrate/src/main.rs

@@ -0,0 +1,3 @@
+fn main() {
+    println!("Hello, world (subcrate)!");
+}