Stats: Create missing ghost (loading) views

[staskus]

Fixes #23059

Created missing ghost loading views:

• For 3-column cell
• For a single value cell
• For a line chart

Solution

We use Ghostable extension implemented in WordPressSharedUI which animates the top leaf views.

• Improved StatsGhostTopCell to support dynamic input of the "number of columns".
• Added StatsGhostSingleValueCell to support ghost loading of single value cells, such as Total Subscribers
• Created StatsGhostLineChartCell to create a dummy line chart path and mask ghostable layer

RPReplay_Final1714735717.MP4

To test:

For easier testing, set a slow Network Link Conditioner setting.

1. Open Stats -> Subscribers
2. Observe new ghostable loading views:

• Single value for Total Subscribers
• Line chart for Subsribers chart
• 2 columns for Subscribers list
• 3 columns for Emails

3. Change orientation and switch between dark/light mode and confirm the view adapts

Regression Notes

1. Potential unintended areas of impact

Places that use StatsGhostTopCell should continue working as before, since I set 2 column scenario as default

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

Manual testing

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.

Testing checklist:

• WordPress.com sites and self-hosted Jetpack sites.
• 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 Jetpack Alpha by scanning the QR code below to install the corresponding build.

	App Name	Jetpack Alpha
	Configuration	Release-Alpha
	Build Number	pr23146-edd95a6
	Version	24.8
	Bundle ID	com.jetpack.alpha
	Commit	edd95a6
	App Center Build	jetpack-installable-builds #8829

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 WordPress Alpha by scanning the QR code below to install the corresponding build.

	App Name	WordPress Alpha
	Configuration	Release-Alpha
	Build Number	pr23146-edd95a6
	Version	24.8
	Bundle ID	org.wordpress.alpha
	Commit	edd95a6
	App Center Build	WPiOS - One-Offs #9783

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

[osullivanchris]

Looks cool!

[guarani]

This works very well! Thanks for handling all the loading views.

I left some minor comments, feel free to merge as-is.