[Woo POS] Create POS Full Screen Cover

[staskus]

Description

[Feel free to take part of this and close it or develop on top of it]

POS Full Screen Cover Shows a full screen cover that automatically manages modal hierarchy.
This is a wrapper around SwiftUI's fullScreenCover that integrates with POS modal system.

Full screen covers automatically establish a new presentation layer, so:

• Modals/sheets from views behind the cover will not show
• Modals/sheet within the cover content will show normally
• Multiple covers can be stacked with proper hierarchy management

Usage is exactly the same as fullScreenCover, using posFullScreenCover which behaves in the exact same way, plus has awareness of posSheet and posModal.

Steps to reproduce

Please test on a task/create-pos-full-screen-cover-test branch that incorporates a test view to showcase different scenarios. https://github.com/woocommerce/woocommerce-ios/compare/task/create-pos-full-screen-cover-test?expand=1

1. Open menu
2. Select setup
3. Try presenting different sheets, modals, overlays on top of overlays to confirm the behavior

Testing information

Screenshots

full.flow.mov

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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 in WooCommerce iOS Prototype by scanning the QR code below to install the corresponding build.

	App Name	WooCommerce iOS Prototype
	Build Number	pr16007-a68ea24
	Version	23.0
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	a68ea24
	Installation URL	3764f4uk2joko

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

[staskus]

Periphery is failing a CI for an annoying reason since these modifiers are not used, but I'm building them to be used in the future 🤦

[iamgabrielma]

Thanks for working on this, it works great for all the use cases presented in task/create-pos-full-screen-cover-test.

I've added periphery:ignore to the lines that came up in buildkite so these pass CI for now, and we can remove these as soon as we use the full screen cover.

I'll go ahead and merge this one into trunk for the moment 🙇