Add the block drag and drop feature and method to /my/tests/behat

Signed-off-by: uhunkler <urs.hunkler@unodo.de>
Add a Scenario to test drag and drop on the /my page with the clean theme

Signed-off-by: uhunkler <urs.hunkler@unodo.de>
Change the indent in the feature file.

Signed-off-by: uhunkler <urs.hunkler@unodo.de>
Add 2 scenarios

_ drag 2 blocks into the content area and drag one block back into the empty right column
_ position one block in the content area via the block region settings page
MDL-44326 WIPP: Fix all other references to DD and add tests