[Backport] Fix error when generating urn catalog for empty misc.xml

[gelanivishal]

Original Pull Request

#11686

Fix error when generating urn catalog for empty misc.xml

Description

Fix error when generating urn catalog for existing empty misc.xml. I fixed this by creating another DomDocumentFactory, for PhpStorm specific misc.xml. This factory checks if the passed data is empty, and if so, create the misc.xml xml structure that \Magento\Developer\Model\XmlCatalog\Format\PhpStorm expects.

I also changed \Magento\Framework\DomDocument\DomDocumentFactory to follow the Magento 2 guidelines and added a Test class for this factory to define the behavior.

Fixed Issues (if relevant)

1. Error generating URN-catalog when blank one exists #5188

Manual testing scenarios

1. rm .idea/misc..xml
2. touch .idea/misc.xml
3. bin/magento dev:urn-catalog:generate .idea/misc.xml

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)

[ihor-sviziev]

Hi,
Unit tests failed, could you recheck it?
PS: It looks like in 2.1.x line we have older phpunit version and unit tests need to be updated.

[sidolov]

@gelanivishal , I am closing this PR now due to inactivity.
Please reopen and update if you wish to continue.
Thank you for the collaboration!