[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-api/src/main/kotlin/org/jetbrains/kotlin/gradle/dsl/kotlinTopLevelExtensionConfig.kt

@@ -40,7 +40,7 @@ interface ExperimentalExtensionConfig {
 /**
  * Different modes that can be used to set the level of issue reporting for [KotlinTopLevelExtensionConfig.explicitApi] option.
  */
-enum class ExplicitApiMode(private val cliOption: String) {
+enum class ExplicitApiMode(val cliOption: String) {
     /** Report issues as errors. */
     Strict("strict"),
 

libraries/tools/kotlin-gradle-plugin-api/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/pm20/KotlinGradleFragment.kt

@@ -31,6 +31,8 @@ interface KotlinGradleFragment : KotlinModuleFragment, HasKotlinDependencies, Ko
 
     fun refines(other: NamedDomainObjectProvider<KotlinGradleFragment>)
 
+    override val directRefinesDependencies: Iterable<KotlinGradleFragment>
+
     override fun dependencies(configureClosure: Closure<Any?>) =
         dependencies f@{ project.configure(this@f, configureClosure) }