[Backport] #17744 Adding logic to get default billing address used on Cart and Checkout

[gelanivishal]

Original PR

#18095

Description

Fixing the bug when the cart is virtual and the estimate was getting the shipping address instead billing address.

Fixed Issues

1. Virtual-only quotes use default shipping address for estimation instead of default billing address #17744: Virtual-only quotes use default shipping address for estimation instead of default billing address

Manual testing scenarios

First scenario

1. Register a billing and a shipping address (Diferents)
2. Add a virtual product to cart
3. The address used in the estimation must be the billing address

Second scenario

1. Register a billing and a shipping address (Diferents)
2. Add a virtual product to cart
3. Add a simple product
4. The address used in the estimation must be the shipping address

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
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[magento-engcom-team]

Hi @VladimirZaets, thank you for the review.
ENGCOM-3316 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.