fix: raise debuggerAttached only if app is restarted

[rosen-vladimirov]

PR Checklist

• The PR title follows our guidelines: https://github.com/NativeScript/NativeScript/blob/master/CONTRIBUTING.md#commit-messages.
• There is an issue for the bug/feature this PR is for. To avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it.
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• Tests for the changes are included.

What is the current behavior?

In case there's no Developer Disk Image on iOS device, applying a change in code during debug, leads to many crashes and incorrect behavior, as CLI raises debuggerAttached event incorrectly.

What is the new behavior?

You are able to debug in Sidekick without Developer Disk Image

Fixes/Implements/Closes #[Issue Number].