[Woo POS] Coupons: Present different views when discerning from no coupons in store vs empty search

[iamgabrielma]

Closes WOOMOB-410

Description

This PR updates the PointOfSaleItemListEmptyView to show slightly different empty views when we find no coupons from store fetch vs no coupons from search. Finding no coupons from search will show a different text, as well as no CTA to create a coupon.

Testing information

• Update PointOfSaleCouponService.providePointOfSaleCoupons to return .init(items: [], hasMorePages: false).
• Navigate to POS > Coupons.
• Observe the existing empty view, tap on search, look for a term.
• Observe the empty view is different and has no CTA.

Screen.Recording.2025-05-02.at.11.38.11.mov

PD: The flicker in the video is because we return empty immediately for debugging

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[wpmobilebot]

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

	App Name	WooCommerce iOS Prototype
	Build Number	29629
	Version	PR #15578
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	65fd950
	Installation URL	022d67s9lgeq8

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