[Forwardport] Resolve incorrect scope code selection when the requested scopeCode is null

[mage2pratik]

Original Pull Request

#16940

Description

• resolves an issue whereby the incorrect scope could be returned when attempting to resolve a scope with a requested scopeCode of null
• simplify the scope resolver logic to a avoid multiple if conditional checks
• move scope interface class to an alias of the class
• update docblock on the expected values available for scopeCode

Resolves #16939

Fixed Issues (if relevant)

1. Incorrect configuration scope is occasionally returned when attempting to resolve a null scope id #16939: Incorrect configuration scope is occasionally returned when attempting to resolve a null scope id

Manual testing scenarios

1. See Incorrect configuration scope is occasionally returned when attempting to resolve a null scope id #16939 for steps to repeat issue + confirm issue is not present when these changes are active

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 on Travis CI are green)

[magento-engcom-team]

Hi @mage2pratik. Thank you for your contribution
Here is some useful tips how you can test your changes using Magento test environment.
Add the comment under your pull request to deploy test or vanilla Magento instance:

• @magento-engcom-team give me test instance - deploy test instance based on PR changes
• @magento-engcom-team give me 2.3-develop instance - deploy vanilla Magento instance

For more details, please, review the Magento Contributor Assistant documentation

[magento-engcom-team]

Hi @rogyar, thank you for the review.
ENGCOM-4458 has been created to process this Pull Request

[m2-assistant]

Hi @mage2pratik, thank you for your contribution!
Please, complete Contribution Survey, it will take less than a minute.
Your feedback will help us to improve contribution process.