Kotlin DSL. Add version extension (Kotlin#1939)

Author: turansky

buildSrc/build.gradle.kts

@@ -0,0 +1,11 @@
+plugins {
+    `kotlin-dsl`
+}
+
+repositories {
+    gradlePluginPortal()
+}
+
+kotlinDslPluginOptions {
+    experimentalWarning.set(false)
+}

buildSrc/src/main/kotlin/Projects.kt

@@ -0,0 +1,4 @@
+import org.gradle.api.Project
+
+fun Project.version(target: String): String =
+    property("${target}_version") as String