Fix retain cycle in GutenbergViewController

[kean]

Fix some of the occurrences of #20647, namely the ones references in #20647 (comment).

RCA

PrepublishingViewController had a retain cycle "thanks" to assign(to:).

When "Tags" screen was presented this property was called for the first time:

private lazy var presentedVC: DrawerPresentationController? {
	return (navigationController as? PrepublishingNavigationController)?.presentedVC
}

I haven't followed the entire memory graph, but this property was evidently indirectly retaining the main GutenbergViewController. And because PrepublishingViewController had a retain cycle, it was also permanently retaining whatever was referenced by presentedVC.

To test:

• Set the breakpoint on GutenbergViewController/deinit
• Follow the steps from EXC_BREAKPOINT: managedObjectContext #20647 (comment)
• Verify that the deinit is called

Regression Testing

• Verify that publishing and settings tags still work

Regression Notes

1. Potential unintended areas of impact: Gutenberg
2. What I did to test those areas of impact (or what existing automated tests I relied on): n/a
3. What automated tests I added (or what prevented me from doing so): n/a

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.

UI Changes testing checklist:

• Portrait and landscape orientations.
• Light and dark modes.
• Fonts: Larger, smaller and bold text.
• High contrast.
• VoiceOver.
• Languages with large words or with letters/accents not frequently used in English.
• Right-to-left languages. (Even if translation isn’t complete, formatting should still respect the right-to-left layout)
• iPhone and iPad.
• Multi-tasking: Split view and Slide over. (iPad)

[wpmobilebot]

📲 You can test the changes from this Pull Request in WordPress Alpha by scanning the QR code below to install the corresponding build.

	App Name	WordPress Alpha
	Configuration	Release-Alpha
	Build Number	pr22265-b765975
	Version	23.9
	Bundle ID	org.wordpress.alpha
	Commit	b765975
	App Center Build	WPiOS - One-Offs #8237

Automatticians: You can use our internal self-serve MC tool to give yourself access to App Center if needed.

[wpmobilebot]

📲 You can test the changes from this Pull Request in Jetpack Alpha by scanning the QR code below to install the corresponding build.

	App Name	Jetpack Alpha
	Configuration	Release-Alpha
	Build Number	pr22265-b765975
	Version	23.9
	Bundle ID	com.jetpack.alpha
	Commit	b765975
	App Center Build	jetpack-installable-builds #7261

Automatticians: You can use our internal self-serve MC tool to give yourself access to App Center if needed.

[twstokes]

LGTM @kean! I couldn't reproduce the crash when following the steps in #20647 (comment). I was able to reproduce the crash using when rolling back to 4fc94b6. 🚀

[alpavanoglu]

To make sure I understand it correctly: The cycle was due to passing directly self rather than using assign right?

[kean]

The .assign(to: \.keyboardShown, on: self) method retains self, which is a common issue in Combine.

[alpavanoglu]

Thank you for the fix Alex!

[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

Generated by 🚫 dangerJS

[wpmobilebot]

	1 Warning
⚠️	This PR is assigned to the milestone 24.0. The due date for this milestone has already passed. Please make sure to get it merged by then or assign it to a milestone with a later deadline.

Generated by 🚫 Danger