tests: integrate pub/sub sample system tests that are still useful

[feywind]

Work in progress for now.

[gemini-code-assist]

Code Review

This pull request introduces a comprehensive testing framework for Pub/Sub, including unit tests for common utilities and system tests for core operations like topic creation and message publishing. It also adds a TestResources class to manage resource lifecycle and prevent naming conflicts. Key feedback includes addressing a potential memory leak in the message listener timeout logic, improving the testability of the cleanup utility by using the provided timestamp provider instead of a direct call to Date.now(), and removing redundant any type assertions for better type safety.

[gemini-code-assist]

The 'message' listener is not removed if the promise rejects due to a timeout. This can lead to memory leaks or unexpected behavior in the test suite if a message arrives after the timeout. It is better to explicitly remove the listener in the timeout path.

    const message = await new Promise<Message>((resolve, reject) => {
      const timeout = setTimeout(() => {
        subscription.removeListener('message', messageHandler);
        reject(new Error('Timeout'));
      }, 10000);
      function messageHandler(m: Message) {
        clearTimeout(timeout);
        m.ack();
        resolve(m);
      }
      subscription.once('message', messageHandler);
    });

[gemini-code-assist]

Use this.tokenMaker.timestamp() instead of Date.now() to ensure consistency with the rest of the class and to allow for deterministic testing of the cleanup logic. The current implementation makes the unit tests dependent on the system clock.

Suggested change

	const timeDiff = (Date.now() - createdAt) / (1000 * 60 * 60);
	const timeDiff = (this.tokenMaker.timestamp() - createdAt) / (1000 * 60 * 60);