MQE-1541

[soumyau]

Entending xsd validation checks to below commands as per recent discussions -

1. run:test
2. run:failed
3. run:group

Updated documentation and fixed review comments from #356 (review)

Description

Fixed Issues (if relevant)

1. magento/magento2-functional-testing-framework#<issue_number>: Issue title
2. ...

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/verification tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)
• Changes to Framework doesn't have backward incompatible changes for tests or have related Pull Request with fixes to tests

[coveralls]

Coverage increased (+1.1%) to 55.502% when pulling f3f53c5 on MQE-1541 into 0e18c22 on develop.