Fix the issue of detail view of SplitViewController when switching out-in the app

[suhaibabsi-inst]

refs: MBL-18549
affects: Student, Teacher
release note: Fixed the issue where app doesn't refresh shown page properly after switching to another app

Issue Analysis

Upon testing on an isolated case, turned out that UISplitViewController always report collapse then expansion whenever app is put to background. For that, CoreSplitViewController in that case calls delegate's methods of:

func splitViewController(_ splitViewController: UISplitViewController, separateSecondaryFrom primaryViewController: UIViewController) upon expansion.

func splitViewController(_ splitViewController: UISplitViewController, collapseSecondary secondaryViewController: UIViewController, onto primaryViewController: UIViewController) upon collapsing.

Which causes the unnecessary disruption on SplitView, although nothing was actually changed from that perspective.

To get around this issue, a new property preBackgroundedSecondaryController to cache secondary view controller when the app is about to be backgrounded. And use that in the expansion delegate's method, instead of executing the DefaultViewProvider logic there, which assumes a real expansion is going on.

One note though, I think we need to rethink the protocol DefaultViewProvider as the main way to extract a secondary view controller in case of expansion. Apparently, it is not being utilized in course details except for home and assignments tabs.

Test Plan

See ticket's description.

Checklist

• Follow-up e2e test ticket created
• A11y checked
• Tested on phone
• Tested on tablet
• Tested in dark mode
• Tested in light mode
• Approve from product

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Teacher Build QR Code:

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Student Build QR Code:

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Release Note:

Fixed the issue where app doesn't refresh shown page properly after switching to another app

Affected Apps: Student, Teacher

MBL-18549

Coverage	New %	Master %	Delta
Canvas iOS	91.52%	91.51%	0.01%

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