[EY] Support CORS for GraphQL

[magento-engcom-team]

As a web developer, I want Magento to support the CORS standard:

https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS

so that I can develop my applications according to defined best practices. 

Use env for settings not system config

Other Issues:

Related issue: https://github.com/magento/magento2/issues/28561 (original issue: #8399)

Acceptance Criteria:

Implement CORS support as detailed here: https://enable-cors.org/server.html

[magento-engcom-team]

The issue was exported from the internal JIRA. The link to the original JIRA issue: https://jira.corp.magento.com/browse/MC-39743

[m2-assistant]

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[m2-assistant]

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[engcom-November]

CORs support for GraphQl is not available in Magento which is the existing behavior of Magento. Hence considering this as feature request.
However this (package)[https://github.com/graycoreio/magento2-cors] allows you to securely add the necessary CORS headers to the Magento 2 GraphQL or REST APIs with ease.