Allow live transformation to be cancelled or avoided when importing large source datasets

[JohannaOtt]

Version 4.0.0.SNAPSHOT Build 617913794

During data import and live transformation, users cannot continue working at the alignment. While this is unproblematic for smaller datasets (primary hale studio use case), creating alignments can get more circuitous when waiting for data import and live transformation without being able to go on with the alignment. It should be checked if it would be possible to execute these processes as background processes and which consequences that would have for the usability of the product (source/transformed data views, adding cells during live transformation,...)