Creating javadocJar task for every project produces lots of unnecessary
tasks, some project don't even have code. Jar task without outDir
property set fails idea import with gradle 5.0+
1. There is no need to specify repositories.
2. We don't use 'org.jetbrains.kotlin:gradle-api:1.6' anymore.
3. kotlin-serialization-unshaded does not need dependencies,
because it does not contain source code (it simply packages jar).
Split import handlers into multiple files
Add empty Maven handler for Android Studio
Add testRuntime dependency on kx-serialization-plugin for all modules which require compiler
plugins in test classpath