introduce experimental scala-api

[robstoll]

Platform (all, jvm, js, android): scala Extension (none, kotlin 1.3): none

Code related feature

some code is already committed but we have not yet created an artifact so far. The following things need to be done in addition

• [ ] rename atrium-scala to atrium-scala2 as we are most likely going to use atrium-scala for Scala 3
• [ ] create a bundle module
• [ ] setup publishing for atrium-scala2
• [ ] use atrium-logic instead of domain-builders
• [ ] adjust issue templates, include scala as platform (maybe rename platform to something else?)