Feature/lerna fix upgrade

[MKaHead]

Fix: Now, finally, only the packages that need it will be published. Furthermore upgrade to lerna 6. the makers of nx have taken over lerna under the bonnet there is now also nx which handles caching and dependencies very well. We will not use the caching completely for the time being, because our use case is not too strong yet. We benefit from the default better speed.

Merge Checklist:

• [x] Code selfreview has been performed (Best Practices).
• [x] Tests are sufficient.
• [x] Documentation is up to date.
• [x] Changelog is up to date.
• [x] Typescript typings for properties are up to date.
• [x] Designers approved changes or no approval needed.
• [x] Dependencies to other components still work.

[markus-walther]

Fix: Now, finally, only the packages that need it will be published.

I think 'that need it' means 'that Lerna detected as changed (direct, or transitively)', correct?