## Summary
**What** — What changes are introduced in this PR?
- show thumbnail on the product variant list
- refactor variant image editor state management
- await revalidation before rendering form
**Testing** — How have these changes been tested, or how can the reviewer test the feature?
Manual testing
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## Checklist
Please ensure the following before requesting a review:
- [x] I have added a **changeset** for this PR
- Every non-breaking change should be marked as a **patch**
- To add a changeset, run `yarn changeset` and follow the prompts
- [ ] The changes are covered by relevant **tests**
- [x] I have verified the code works as intended locally
- [ ] I have linked the related issue(s) if applicable
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