Let missing routes match catch-all routes

[elia]

WHY are these changes introduced?

I got a message for missing routes for the collection route, but I just renamed it to catch collection handles that included slashes: routes/collections.$handle.ts → routes/collections.$.ts.

The new route will still cover for requests falling under the original one.

WHAT is this pull request doing?

This change will make the missing-routes library recognize routes using $.

HOW to test your changes?

Rename the collection route to collections.$.ts and run shopify hydrogen check routes.

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

[blittle]

Thank you! It looks good!