Refactor NotificationsViewController & Add NotificationsViewModel

[alpavanoglu]

Refs: pcdRpT-5aB-p2

This PR is a first of a following chain to reduce the complexity of NotificationsViewController by attempting to decouple logic from the view. So we can add and modify features quickly in our next project.

I will isolate the changes semantically to make testing and reviewing easier. So all the changes here are about lastSeen logic.

Testing Steps

1. Install & Login to Jetpack app.
2. App badges must be enabled. Check current badge count.
3. Navigate to Notifications
4. ✅ Check if viewing the Notifications updates the badges as it should.

Regression Notes

1. Potential unintended areas of impact
   The refactored areas themselves

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

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

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.

[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	pr22351-15a74fe
	Version	24.1
	Bundle ID	org.wordpress.alpha
	Commit	15a74fe
	App Center Build	WPiOS - One-Offs #8595

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	pr22351-15a74fe
	Version	24.1
	Bundle ID	com.jetpack.alpha
	Commit	15a74fe
	App Center Build	jetpack-installable-builds #7624

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

[salimbraksa]

@alpavanoglu Code changes look good to me, but I wasn't able to test the changes. The App Badges is always 0, this is not a regression, it was always the case for me. Perhaps @hassaanelgarem can help test the PR?

N.B. I made sure App Badges is enabled.

[mokagio]

I'm going to bump this to the next release because we'll be code freezing 24.1 today and this hasn't been reviewed yet.

If these changes cannot wait two weeks and it's important that it makes it into this release, let me know and we'll organize a new beta once ready.

[hassaanelgarem]

@salimbraksa @alpavanoglu The testing instructions are a bit confusing to me. Are we testing the in-app badge over the notifications tab bar icon? Or are we testing the App Icon Badges?

The in-app badge works as expected.
The App Badge has never worked for me as well. @alpavanoglu Are you sure this is something we support? If yes, can you provide more detailed testing instructions?

[alpavanoglu]

@hassaanelgarem @salimbraksa

The testing steps are for App Badges, and not in-app badge. Do you test it on a device or a simulator? I don't know why App badges are not working for you. They do work on my device just fine.

When we view the Notifications tab, the last seen value is checked to reset the badges afaik. I can send a screen recording over slack (I won't post here as I use my own account to see badges) if that would help.

The changes are simply copying over the logic to VM and I added tests. I mostly added the manual testing steps as "just in case".

[salimbraksa]

LGTM! 🚀