[Catalog] Fix user value verification when adding product with multiselect custom option to cart

[Den4ik]

Description (*)

This PR provide fix for verification of selected custom options

Fixed Issues (if relevant)

1. Can't add product to cart with customizable options (type checkbox) through REST API #23863: Can't add product to cart with customizable options (type checkbox) through REST API

Manual testing scenarios (*)

1. Add product with 2 and more selected custom options to cart via api

Questions or comments

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds are green)

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[magento-engcom-team]

Hi @swnsma, thank you for the review.
ENGCOM-5525 has been created to process this Pull Request
✳️ @swnsma, could you please add one of the following labels to the Pull Request?

Label	Description
Auto-Tests: Covered	All changes in Pull Request is covered by auto-tests
Auto-Tests: Not Covered	Changes in Pull Request requires coverage by auto-tests
Auto-Tests: Not Required	Changes in Pull Request does not require coverage by auto-tests

[engcom-Alfa]

✔️ QA Passed

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