Fix ability to move merch item under another collection

[dowhep]

Info

Closes #433.

Description

What changes did you make? List all distinct problems that this PR addresses. Explain any relevant
motivation or context.

enable collection property to be editable through PATCH /item/:uuid

Changes

edited the logic for merch store service over itemedit

Type of Change

• Patch (non-breaking change/bugfix)
• Minor (non-breaking change which adds functionality)
• Major (fix or feature that would cause existing functionality to not work as
  expected)
• Documentation (A change to a README/description)
• Continuous Integration/DevOps Change (Related to deployment steps, continuous integration
  workflows, linting, etc.)
• Other: (Fill In)

If you've selected Patch, Minor, or Major as your change type, make sure to bump the version before merging in package.json!

Testing

I have tested that my changes fully resolve the linked issue ...

• locally.
• on the testing API/testing database.
• with appropriate Postman routes. Screenshots are included below.

Checklist

• I have performed a self-review of my own code.
• I have followed the style guidelines of this project.
• I have appropriately edited the API version in the package.json file.
• My changes produce no new warnings.

Screenshots

Please include a screenshot of your Postman testing passing successfully.

[github-actions]

Thanks for contributing!
If you've made changes to the API's functionality, please make sure to bump the package
version—see this guide to semantic versioning for details—and
document those changes as appropriate.

[nik-dange]

one quick question

[nik-dange]

If you look at line 341, there's a call to MerchandiseItemModel.merge(). However, line 352 (merchItemRepository.upsertMerchItem()) calls MerchandiseItemModel.merge() internally. What's the reason for this difference? Is there a need to call the model's merge method directly prior to checking if there's an updated collection?

[dowhep]

we merge at line 341 so that we can immediately test whether the merged item is a valid item or not on line 342, although upsertMerchItem does call merge internally, it does not do the checking by itself and requires external check for validations. In addition, merge is a fast operation so we can kinda use it freely.

[dowhep]

closing this bc @nik-dange addressed it in his pr