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`).

Original commit: 8a82c1618c

jps/jps-common/build.gradle.kts

@@ -1,6 +1,8 @@
 
-apply { plugin("kotlin") }
+plugins {
-apply { plugin("jps-compatible") }
+    kotlin("jvm")
+    id("jps-compatible")
+}
 
 dependencies {
     compile(projectDist(":kotlin-stdlib"))

jps/jps-plugin/build.gradle.kts

@@ -1,5 +1,7 @@
-apply { plugin("kotlin") }
+plugins {
-apply { plugin("jps-compatible") }
+    kotlin("jvm")
+    id("jps-compatible")
+}
 
 val compilerModules: Array<String> by rootProject.extra