Drop Kotlin multiplatform

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As Kotysa is written in Kotlin I gave my best to make it KMM, Kotlin Multiplatform Mobile, to provide the Kotysa ORM for mobile devs with SqLite support (on Android only for now). I imagined adding iOS later but I don't own an Apple computer so it would be hard to test...

This multiplatform support is the most time-consuming part of the dev for me, and Kotlinmultiplatform compilation is a real mess ! Making my computer crash several times a day.

Since Kotlin 1.9.20 expect/actual are even stricter than before, I couldn't make it work with this project.

I will drop multiplatform, I then can greatly simplify Kotysa modules and the Gradle compilation, so I can focus on the JVM evolutions only.