set explicit Gradle root project name
set explicit Gradle root project name

... to make it independent of the folder name into which people clone ArchUnit, and to disambiguate the root from the `archunit` subproject.

Signed-off-by: Peter Gafert <cdbfcea01cf62f959f8b10da948a53f2869d9b6c@tngtech.com>

TNG/ArchUnit,TNG/ArchUnit