Switch to flickwerk for loading patches

[senemsoy]

Summary

Solidus has moved to using app/patches for monkey patching core classes using the flickwerk gem. This change updates the starter frontend to be consistent with that.

This commit closes https://github.com/solidusio/solidus_starter_frontend/issues/427 and should resolve the issue here: https://github.com/solidusio/solidus/issues/4877

Checklist

Check out our PR guidelines for more details.

The following are mandatory for all PRs:

• [ ] I agree that my PR will be published under the same license as Solidus.
• [ ] I have written a thorough PR description.
• [ ] I have kept my commits small and atomic.
• [ ] I have used clear, explanatory commit messages.

The following are not always needed:

• 📖 I have updated the README to account for my changes.
• 📑 I have documented new code with YARD.
• 🛣️ I have opened a PR to update the guides.
• ✅ I have added automated tests to cover my changes.
• 📸 I have attached screenshots to demo visual changes.

[jarednorman]

We should probably get tests working again and run them before we merge.