Introduce Abort Initialisation After TearDown

[terminal-overflow]

📺 What

Introduces the concept of aborting initialisation if Bigscreen Player has already been torn down.

This prevents the issue where, if BSP is torn down during initialisation, TypeError: Cannot read properties of null (reading 'manifestType') or Cannot read properties of undefined (reading 'time') is thrown, depending on where mediaSources.time().manifestType is called. These errors can be caused by tearDown() tearing down and de-referencing mediaSources whilst BSP is in the process of initialising.

🛠 How

• Introduce an AbortSignal which keeps the state of if BSP has been torn down. Also provides a throwIfAborted error which throws an AbortError.
  • The AbortError has a custom name and message.
• Call signal.abort() on invocation of tearDown().
• Add unit tests for abortutils.
• Add integration tests to bigscreenplayer and playercomponent.

✅ Testing

Test engineer sign off	❌

[ShiningTrapez]

LGTM 🚀