Change returning value for attribute option cretaion from 'true' to option record

[k-raputa]

Description

Fix for: Successful attribute option POST returns 'true', not the option hash or value

Fixed Issues (if relevant)

1. Successful attribute option POST returns 'true', not the option hash or value #6300: Successful attribute option POST returns 'true', not the option hash or value

Manual testing scenarios

1. POST an new option value using /V1/products/attributes/{attributeCode}/options. Request body looks like {"option": {"label": "FOOBAR"} }
2. Response should contain new inserted option data

[magento-cicd2]

All committers have signed the CLA.

[mzeis]

Hi @k-raputa, thanks for your PR!

It looks like #6300 and #8810 are duplicates. For #8810, there is a PR #12920 which is in review. I'll ping @okorshenko to decide what to do.

[mzeis]

@k-raputa Please, also create PRs only from your personal fork and don't create branches in the M2 repository directly. Thank you!

[okorshenko]

Please create the branch in your personal fork