Implement new minimal extension point for providing (new) script definitions to idea

#KT-27817 fixed

libraries/scripting/intellij/build.gradle.kts

@@ -0,0 +1,26 @@
+
+plugins {
+    kotlin("jvm")
+    id("jps-compatible")
+}
+
+jvmTarget = "1.6"
+
+dependencies {
+    compile(project(":kotlin-script-runtime"))
+    compile(project(":kotlin-stdlib"))
+    compile(project(":kotlin-scripting-common"))
+    compileOnly(intellijCoreDep()) { includeJars("intellij-core") }
+}
+
+sourceSets {
+    "main" { projectDefault() }
+    "test" { }
+}
+
+standardPublicJars()
+
+ideaPlugin()
+
+publish()
+

libraries/scripting/intellij/src/kotlin/script/experimental/intellij/scriptDefinitionProvider.kt

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+package kotlin.script.experimental.intellij
+
+import com.intellij.openapi.extensions.ExtensionPointName
+import com.intellij.openapi.extensions.Extensions
+import com.intellij.openapi.project.Project
+import java.io.File
+
+interface ScriptDefinitionsProvider {
+    val id: String
+
+    fun getDefinitionClasses(): Iterable<String>
+
+    fun getDefinitionsClassPath(): Iterable<File>
+
+    fun useDiscovery(): Boolean
+
+    companion object {
+        val EP_NAME: ExtensionPointName<ScriptDefinitionsProvider> =
+            ExtensionPointName.create<ScriptDefinitionsProvider>("org.jetbrains.kotlin.scriptDefinitionsProvider")
+    }
+
+}