Simplify Fakes into a Swift package

[mokagio]

Description

See https://linear.app/a8c/issue/AINFRA-473.

Based on top of #15755 and based off the original work from #15678 .

This first PR moves Fakes from being a framework to being a Swift package. Notice that this framework has no tests because it consists of a protocol, and helper, and generated files.

Steps to reproduce & Testing information

See green CI.

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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. — N.A.

[dangermattic]

	2 Warnings
⚠️	Modules/Package.swift was changed without updating its corresponding Package.resolved. Please resolve the Swift packages as appropriate to your project setup (e.g. in Xcode or by running swift package resolve).
⚠️	This PR is larger than 300 lines of changes. Please consider splitting it into smaller PRs for easier and faster reviews.

Generated by 🚫 Danger

[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	30605
	Version	PR #15772
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	fd9f830
	Installation URL	09ngqgbf2ohe8

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

[joshheald]

👍 Thanks again @mokagio! Tested generation puts the files in the right places too.