JPS build: add idea settings to build.gradle.kts

#KT-29323 Fixed

buildSrc/build.gradle.kts

@@ -87,6 +87,7 @@ repositories {
 
     jcenter()
     maven("https://jetbrains.bintray.com/intellij-third-party-dependencies/")
+    maven("https://plugins.gradle.org/m2/")
 }
 
 dependencies {
@@ -97,6 +98,8 @@ dependencies {
 
     compile("com.github.jengelman.gradle.plugins:shadow:${property("versions.shadow")}")
     compile("org.jetbrains.intellij.deps:asm-all:7.0")
+
+    compile("gradle.plugin.org.jetbrains.gradle.plugin.idea-ext:gradle-idea-ext:0.4.2")
 }
 
 samWithReceiver {