[PLAT-7263] Disable app hang detection in app extensions

[nickdowell]

Goal

App extensions have a different life cycle and environment that make the hang detection mechanism unsuitable.

• Depending on the type of extension, the run loop is not necessarily dedicated to UI.
• The host app or other extensions run by it may trigger false positives.
• The system may kill app extensions without any notification.

Changeset

Disables app hang detection in app extensions.

Improves the logic of +[BSG_KSSystemInfo isRunningInAppExtension] by querying the Info.plist's NSExtensionPointIdentifier rather than CFBundlePackageType (which would erroneously cause YES to be returned for some versions of Xcode's xctest unit test runner.)

Testing

Manually verified in a Widget app extension.

[github-actions]

Infer: No issues found 🎉

OCLint: No issues found 🎉

Bugsnag.framework binary size did not change - 1,156,600 bytes

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