fix: handle notification timeout correctly when set to 0

[ndoschek]

What it does

• Fix timeout logic to properly handle explicit timeout of 0
• Change condition from falsy check to undefined check to preserve 0 value if set explicitly
• Add unit tests for getTimeout method covering various timeout scenarios
• Add sample commands demonstrating persistent and vanishing notifications

How to test

• Test the different commands with either 0ms, 500ms or default notification timeout:
  • Sample Persistent Notification (No Timeout)
  • Sample Vanishing Notification (500ms Timeout)
  • Test Positive Integer (default timeout: 30000ms, unless overridden in the settings notification.timeout)

Follow-ups

Breaking changes

• This PR introduces breaking changes and requires careful review. If yes, the breaking changes section in the changelog has been updated.

Attribution

Contributed on behalf of STMicroelectronics

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• As an author, I have thoroughly tested my changes and carefully followed the review guidelines
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