Explicitly enable Dokka javadocs generation

Actually we don't need javadoc generation for our internal stuff like
':kotlin-gradle-plugin'. But ':kotlin-gradle-plugin-api' is a public api
 and should have properly generated javadocs.

^KT-55520 In Progress

libraries/tools/kotlin-gradle-plugin-api/build.gradle.kts

@@ -4,6 +4,8 @@ plugins {
     id("org.jetbrains.kotlinx.binary-compatibility-validator")
 }
 
+configureDokkaPublication()
+
 dependencies {
     commonApi(platform(project(":kotlin-gradle-plugins-bom")))
     commonApi(project(":kotlin-gradle-plugin-annotations"))