ci/cd: trigger URL checks more, and limit amount

Key changes:

- Run URL checks more frequently on every change.
- Introduce environment variable to randomly select and limit URLs
  tested, this way the tests will provide quicker feedback on code
  changes.

Other supporting changes:

- Log more information about test before running the test to enable
  easier troubleshooting.
- Move shuffle function for arrays for reusability and missing tests.

src/application/Common/Shuffle.ts

@@ -0,0 +1,12 @@
+/*
+  Shuffle an array of strings, returning a new array with elements in random order.
+  Uses the Fisher-Yates (or Durstenfeld) algorithm.
+*/
+export function shuffle<T>(array: readonly T[]): T[] {
+  const shuffledArray = [...array];
+  for (let i = array.length - 1; i > 0; i--) {
+    const j = Math.floor(Math.random() * (i + 1));
+    [shuffledArray[i], shuffledArray[j]] = [shuffledArray[j], shuffledArray[i]];
+  }
+  return shuffledArray;
+}