[PLAT-6311] Ignore hangs while app is in the background

[nickdowell]

Goal

Fatal app hangs have been observed to occur due to OS-level issues when apps move into the background state.

One example is CABackingStoreCollectBlocking() hanging while it cleans up graphics resources. It has been reported that this can take up to 10 seconds, and therefore cause the app to be terminated by the system watchdog.

Since this is not likely to be an app bug or noticed by users (who would observe the app opening on its start screen) it does not make sense to report these hangs as fatal / unhandled errors that affect the stability score. Apps can be terminated in the background for a number of other reasons.

Changeset

App hangs are now ignored once UIApplicationDidEnterBackgroundNotification has been received and until a subsequent UIApplicationWillEnterForegroundNotification is received.

Testing

E2E tests have been amended to verify 3 additional scenarios:

• App hangs SHOULD NOT be reported if they occur after the app has moved to the background
• App hangs SHOULD be reported if the app starts hanging before going to the background
• App hangs SHOULD be reported if the app hangs after resuming from the background

[github-actions]

Infer: No issues found 🎉

OCLint: No issues found 🎉

Bugsnag.framework binary size increased by 1,000 bytes from 1,119,520 to 1,120,520

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