Stop debug session on prelaunchTask failures (Prevent 100% CPU)

[afterxleep]

⚠️ DRAFT: This PR includes changes from #138, which needs to be merged first.

Description

Very often, VSCode does not always stop the debug session when a preLaunchTask fails, even if configured to do so. It may continue to start the debug server, lingering around using 100% CPU until the user manually interrupts the debug session.

What Changed

This change checks for xcodebuild task failures, displays a "Build failed" message, and immediately stops the debug session.

How to test

• Update a test project so build fails
• Run the debugger
• Confirm the debug session is immediately stopped after build fails and you get a notification
• debugserver process should not be present In Activity Monitor

[afterxleep]

@hyzyla this is an important fix as it severely impacts battery life and performance. (multiple debugserver processes can end up clogging the CPU)

[afterxleep]

I just noticed this issue is more evident if you have VSCode setup to try attach to the debugger even if there are tasks failrues. Leaving it as a draft as it's worth more testing.