[Stats Revamp] Fix Crash when dismissing "Manage Stats Cards" on iPad

[staskus]

Fixes #20003

Description

A crash happens when dismissing "Manage Stats Cards" on iPad after making changes.

This is a classic iOS crash that happens when UIAlertViewController is presented as actionSheet on iPad without specifying sourceView.

Solution

Instead of setting sourceView, I decided to show alert on iPad when there're unsaved changes.

Testing instructions

Case 1:

1. Launch the JP app on the iPad and log in.
2. Open "My Site → Stats".
3. Tap ⚙️ button at the top of the screen.
4. Make some changes by adding or removing active cards.
5. Tap Ⅹ button to close the Manage Stats Cards.
6. Alert should appear, no crash should be happening

Regression Notes

1. Potential unintended areas of impact

None

2. What I did to test those areas of impact (or what existing automated tests I relied on)

None

3. What automated tests I added (or what prevented me from doing so)

None

PR submission checklist:

• I have completed the Regression Notes.
• I have considered adding unit tests for my changes.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

Images & Videos

iPad

Simulator.Screen.Recording.-.iPad.Pro.11-inch.4th.generation.-.2023-01-27.at.09.42.12.mp4

iPhone

Simulator.Screen.Recording.-.iPhone.14.-.2023-01-27.at.09.45.39.mp4

[peril-wordpress-mobile]

	Warnings
⚠️	This PR is assigned to a milestone which is closing in less than 4 days Please, make sure to get it merged by then or assign it to a later expiring milestone

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[wpmobilebot]

You can test the changes in WordPress from this Pull Request by:

• Clicking here or scanning the QR code below to access App Center
• Then installing the build number pr20013-5b38456 on your iPhone

If you need access to App Center, please ask a maintainer to add you.

[wpmobilebot]

You can test the changes in Jetpack from this Pull Request by:

• Clicking here or scanning the QR code below to access App Center
• Then installing the build number pr20013-5b38456 on your iPhone

If you need access to App Center, please ask a maintainer to add you.

[irfano]

Instead of setting sourceView, I decided to show alert on iPad when there're unsaved changes.

Makes sense!
I tested and it doesn't crash anymore.