[My Store] Add support for conditionally storing site summary stats

[rachelmcr]

Part of #8173
⚠️ Depends on #8420 ⚠️

Description

This PR adds support in the Yosemite layer for conditionally storing SiteSummaryStats fetched from remote:

• Adds support for retrieving SiteSummaryStats from storage.
• Adds a saveInStorage parameter to StatsActionV4.retrieveSiteSummaryStats to determine if stats should be stored.
• Updates StatsStoreV4 to support conditionally upserting stats fetched from remote.

Note: For now we only store SiteSummaryStats that are fetched for a single period. The My Store dashboard only needs summary stats for a single period (day, week, month, year) and stats fetched for multiple periods don't need to be stored (used only in the Analytics Hub, for quarter periods).

Testing instructions

1. Build and run the app.
2. Tap "See more" to open Analytics.
3. Confirm the Sessions card loads as expected for different time ranges.

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• 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 by:

• Clicking here or scanning the QR code below to access App Center
• Then installing the build number pr8421-4fcd0eb on your iPhone

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

[peril-woocommerce]

	Warnings
⚠️	This PR is assigned to a milestone which is closing in less than 2 days Please, make sure to get it merged by then or assign it to a later expiring milestone

Generated by 🚫 dangerJS

[Ecarrion]

Code looks good! But now that I think a bit more about the WHY of these changes I think I'm not understanding something 😅

As far as I can tell, this PR is adding the ability to retrieveSiteSummaryStats to store results on the storage layer, right?

But in the PR you say that this is needed for the Dashboard Stats, does that mean that we will be adding this information on the dashboard?

Or did I miss-understood this 😅 ?

[rachelmcr]

But in the PR you say that this is needed for the Dashboard Stats, does that mean that we will be adding this information on the dashboard?

The information is already in the dashboard ("Visitors" and "Conversion rate"), but it's showing inaccurate data:

• Right now, we're computing a site's total visitor count by adding together the visitor count for each of the intervals within a given period (from SiteVisitStats data).
• What we should do in the dashboard —and we're doing already in Analytics Hub — is get the total visitor count for the entire period (from SiteSummaryStats data).

The first approach is inaccurate because visitors are uniques, so the same visitor should only be counted once even if they visit multiple times during the entire period.

Since we're using the accurate method in Analytics Hub, I'm fixing it in the Dashboard stats to make sure there aren't inconsistencies between the stats shown on the two screens.