[KPM] Implement initial IdeaKotlinProjectModelBuilder

- Introduce `kotlin-gradle-plugin-idea` module that allows
to share models between the IDE and KGP

- Add `kotlin-gradle-plugin-idea` to the RuntimePublicAPITest to
ensure binary compatibility

^KT-51262

libraries/tools/kotlin-gradle-plugin-idea/ReadMe.md

@@ -0,0 +1,13 @@
+# Kotlin Gradle Plugin Models shared between IDEA import and KGP
+The classes defined in this module will be available inside the Kotlin Gradle Plugin (KGP) 
+as well as in the IDE import (GradleProject).
+
+## Binary Compatibility: 
+Binary compatibility can be tested by
+`./gradlew :tools:binary-compatibility-validator:clean :tools:binary-compatibility-validator:test`
+
+Binary incompatible changes have to go through a proper deprecation cycle after releases
+
+### Unstable APIs / KotlinGradlePluginApi
+Some APIs are marked with 'KotlinGradlePluginApi' which means, that those are not kept binary compatible and are considered 'unstable'
+from the IDEA perspective. Typically constructors for models are marked like this