feat: Begins update for more modern swift-dependencies implementation.

Sources/TestSupport/TestSupport.swift

@@ -0,0 +1,23 @@
+import Foundation
+
+// swiftlint:disable force_try
+
+/// Helper to create a temporary directory for running tests in.
+///
+/// The temporary directory will be removed after the operation has ran.
+///
+/// - Parameters:
+///   - operation: The operation to run with the temporary directory.
+public func withTemporaryDirectory(
+  _ operation: (URL) throws -> Void
+) rethrows {
+  let tempUrl = FileManager.default
+    .temporaryDirectory
+    .appendingPathComponent(UUID().uuidString)
+
+  try! FileManager.default.createDirectory(at: tempUrl, withIntermediateDirectories: false)
+  try operation(tempUrl)
+  try! FileManager.default.removeItem(at: tempUrl)
+}
+
+// swiftlint:enable force_try