Add example integration tests and configuration

phpunit.integration.xml

...p/code/Met/ExampleMagento2ModuleTesting/Model/Example.php

...ento2ModuleTesting/Test/Integration/Model/ExampleTest.php

...eMagento2ModuleTesting/Test/Integration/_files/orders.php

...ModuleTesting/Test/Integration/_files/orders_rollback.php

...mpleMagento2ModuleTesting/Test/Unit/Model/ExampleTest.php

src/app/code/Met/ExampleMagento2ModuleTesting/composer.json

src/app/code/Met/ExampleMagento2ModuleTesting/etc/module.xml

...pp/code/Met/ExampleMagento2ModuleTesting/registration.php