Use Plugins DSL in Kotlin Gradle scripts

When plugins DSL is used, there is no need to
manually generate typesafe accessors for extensions and
conventions (by running `./gradlew kotlinDslAccessorsSnapshot`).

core/descriptors.runtime/build.gradle.kts

@@ -1,6 +1,8 @@
 import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 
-apply { plugin("kotlin") }
+plugins {
+    kotlin("jvm")
+}
 
 dependencies {
     compileOnly(project(":core:util.runtime"))