[Backport] #18956 Fixes for set root_category_id

[gelanivishal]

Original Pull Request

#18958

Description (*)

Currently is not possible to define the root_category_id in the Project config.php

Fixed Issues (if relevant)

1. Import of RootCategoryId should be possbile (Magento/Store/Model/Config/Importer/Processor/Create.php) #18956 Import of RootCategoryId should be possbile

Manual testing scenarios (*)

• Create a config.php like
• Run bin/magento -n app:config:import

    'scopes' => [
        'websites' => [
            'admin' => [
                'website_id' => '0',
                'code' => 'admin',
                'name' => 'Admin',
                'sort_order' => '0',
                'default_group_id' => '0',
                'is_default' => '0'
            ],
            'de' => [
                'website_id' => '2',
                'code' => 'de',
                'name' => 'DE',
                'sort_order' => '10',
                'default_group_id' => '2',
                'is_default' => '1'
            ]
        ],
        'groups' => [
            [
                'group_id' => '0',
                'website_id' => '0',
                'code' => 'default',
                'name' => 'Default',
                'root_category_id' => '0',
                'default_store_id' => '0'
            ],
            [
                'group_id' => '2',
                'website_id' => '2',
                'code' => 'de',
                'name' => 'DE',
                'root_category_id' => '2',
                'default_store_id' => '2'
            ]
        ],
        'stores' => [
            'admin' => [
                'store_id' => '0',
                'code' => 'admin',
                'website_id' => '0',
                'group_id' => '0',
                'name' => 'Admin',
                'sort_order' => '0',
                'is_active' => '1'
            ],
            'de_de' => [
                'store_id' => '2',
                'code' => 'de',
                'website_id' => '2',
                'group_id' => '2',
                'name' => ' de DE',
                'sort_order' => '10',
                'is_active' => '1'
            ]
        ]
    ]

Expected behavior (*)

• Import of root_category_id is successfully

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 @gelanivishal. 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 2.2-develop instance - deploy vanilla Magento instance

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[magento-engcom-team]

Hi @larsroettig, thank you for the review.
ENGCOM-3480 has been created to process this Pull Request

[magento-engcom-team]

Hi @gelanivishal. Thank you for your contribution.
We will aim to release these changes as part of 2.2.8.
Please check the release notes for final confirmation.

Please, consider to port this solution to 2.3 release line.
You may use Porting tool to port commits automatically.