Incorporate the v3_routeConfig future flag for Remix.

[seanparsons]

WHY are these changes introduced?

These changes are to support an upgrade to the next version of Remix, by using the future flag and supporting libraries to get the code ready for that upgrade in place before the upgrade itself happens.

WHAT is this pull request doing?

• Added the v3_routeConfig flag set to true.
• Created a hydrogen.v3preset function which excludes the routes attribute that the hydrogen.preset function includes because that is incompatible with the flag being turned on.
• Added a hydrogenRoutes function which transforms the route specified in routes.ts to include the virtual routes.
• Rewrote getVirtualRoutes to work without using any node libraries so that it can run in MiniOxygen.
• Updated the example projects to have them use the flag and the changes necessary to use the flag.

HOW to test your changes?

• Follow the steps as described in https://remix.run/docs/en/main/start/future-flags#v3_routeconfig to bring your project in line with the expectations therein.
• Wrap the routes in routes.ts with the hydrogenRoutes function, to add the supporting routes.

Post-merge steps

Checklist

• I've read the Contributing Guidelines
• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've added a changeset if this PR contains user-facing or noteworthy changes
• I've added tests to cover my changes
• I've added or updated the documentation

[shopify]

Oxygen deployed a preview of your refactor/v3_routeconfig_flag branch. Details:

Storefront	Status	Preview link	Deployment details	Last update (UTC)
third-party-queries-caching	✅ Successful (Logs)	Preview deployment	Inspect deployment	January 23, 2025 5:08 PM
Skeleton (skeleton.hydrogen.shop)	✅ Successful (Logs)	Preview deployment	Inspect deployment	January 23, 2025 5:08 PM
metaobjects	✅ Successful (Logs)	Preview deployment	Inspect deployment	January 23, 2025 5:08 PM
classic-remix	- (Logs)	-	Inspect deployment	January 23, 2025 5:08 PM
custom-cart-method	✅ Successful (Logs)	Preview deployment	Inspect deployment	January 23, 2025 5:08 PM

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