Add resolver to determine if quote is virtual

[fooman]

Description (*)

A lot of behaviour in the checkout in particular depends on if the quote is virtual or not, ie if shipping methods need to be offered or if a shipping address should be entered. This PR makes the is_virtual property of the quote available.

Fixed Issues (if relevant)

1. couldn't find any

Manual testing scenarios (*)

1. Add a virtual product to the cart
2. query graphql with something like this

{
  cart(cart_id:"$maskedQuoteId") {    
    is_virtual
  }
}

the result should be a boolean true.
3. Add a simple product to the cart
4. Run the same graphql query again - the result should now be false.

Questions or comments

I did duplicate the _security tests here as well. I believe they could be cut if preferred as the boolean provided by this resolver by itself is not sensitive.

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)

[fooman]

I currently am unable to find what failed in the test:

Happy to look into it once I know what failed.

[lenaorobei]

@magento run Functional Tests build, WebAPI Tests build

[fooman]

@lenaorobei found the culprit. I had a wrong fixture path reference that caused
Uncaught PHPUnit\Framework\Exception: Warning: require(/var/www/html/dev/tests/integration/testsuite/Magento/GraphQl/Catalog/_files/product_virtual.php): failed to open stream: No such file or directory which doesn't seem to get displayed in the report.

[magento-engcom-team]

Hi @lenaorobei, thank you for the review.
ENGCOM-5795 has been created to process this Pull Request
✳️ @lenaorobei, 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

[ghost]

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