Widgets: Share store TZ settings

[ealeksandrov]

Closes: #7564

Description

To make sure we're using store TZ, share it as a parameter to widget extension and use in stats requests.

How

• Adds defaultStoreTimeZoneGMTOffset userdefault property
• Moves Date+StartAndEnd extension to shared WooFoundation module
• Uses shared extension with store timezone in API requests

Note: Testing this is complicated and sometimes I got different stats result in app dashboard and widget.
Stats dashboard uses store TZ for UI, but device TZ for requests:

woocommerce-ios/WooCommerce/Classes/ViewRelated/Dashboard/Stats v4/StoreStatsAndTopPerformersViewController.swift

Lines 206 to 210 in 29c95b9

	// Since the stats charts are based on site time zone, we set the time zone for the stats UI to be the site time zone.
	// On the other hand, when syncing the stats data with the API, we want to use the device time zone to find the time range since the API date parameters
	// have no time zone information and are relative to the site time zone (e.g. 12:00am-11:59pm for "Today" tab).
	let timezoneForStatsDates = TimeZone.siteTimezone
	let timezoneForSync = TimeZone.current

Should we do the same?

Testing Steps

• Set timezone on device and store to be very different. In wp-admin it's in Settings -> General -> Timezone.
• Add orders close to days transitions in both TZs.
• Launch the app.
• Compare stats data on app dashboard and widget.

---

• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[ealeksandrov]

This presentation is picked because we init it same way from API response:

woocommerce-ios/Networking/Networking/Model/Site.swift

Lines 168 to 173 in 29c95b9

	/// Returns the TimeZone using the gmtOffset
	///
	var siteTimezone: TimeZone {
	let secondsFromGMT = Int(gmtOffset * 3600)
	return TimeZone(secondsFromGMT: secondsFromGMT) ?? .current
	}

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[Ecarrion]

Code looks good!

Should we do the same?

I think we should match the way the app fetches & displays information. Because if not the merchant won't know what source of information to trust.

App	Widget

Since the stats charts are based on site time zone, we set the time zone for the stats UI to be the site time zone.

Wouldn't that means that we don't need the site timezone? As we don't show charts?

[Ecarrion]

Suggested change

	/// Timezone of the website
	/// Timezone of the store

[ealeksandrov]

Wouldn't that means that we don't need the site timezone? As we don't show charts?

That's what I think now. Should we close it and maybe get back if we found inconsistencies in testing?

Update: Actually, I think Date+StartAndEnd reuse worth merging. So I reverted TZ sharing (49687de) and updated code to use device TZ (eedc08e).

[Ecarrion]

Update: Actually, I think Date+StartAndEnd reuse worth merging. So I reverted TZ sharing (49687de) and updated code to use device TZ (eedc08e).

Agree specially since we recently added some logs due to a new crash around date parsing.

[Ecarrion]

Wow I don't know why I used startOfToday 🤦