Add ProjectImportProvider for *.gradle.kts file to import it as module

#KT-19466 Fixed

idea/idea-gradle/src/org/jetbrains/kotlin/gradle/GradleKotlinDSLProjectImportProvider.kt

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2010-2017 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jetbrains.kotlin.gradle
+
+import com.intellij.openapi.externalSystem.service.project.wizard.AbstractExternalProjectImportProvider
+import com.intellij.openapi.vfs.VirtualFile
+import org.jetbrains.plugins.gradle.service.project.wizard.GradleProjectImportBuilder
+import org.jetbrains.plugins.gradle.util.GradleConstants
+
+class GradleKotlinDSLProjectImportProvider(builder: GradleProjectImportBuilder)
+    : AbstractExternalProjectImportProvider(builder, GradleConstants.SYSTEM_ID) {
+
+    override fun canImportFromFile(file: VirtualFile): Boolean = file.name.endsWith(".${GradleConstants.EXTENSION}.kts")
+
+    override fun getFileSample(): String? = "<b>Gradle (Kotlin DSL)</b> build script (*.gradle.kts)"
+}

idea/src/META-INF/plugin.xml

@@ -2478,6 +2478,7 @@
     <psi.clsCustomNavigationPolicy implementation="org.jetbrains.kotlin.idea.core.script.dependencies.ScriptDependencySourceNavigationPolicyForJavaClasses"/>
     <resolveScopeProvider implementation="org.jetbrains.kotlin.idea.core.script.dependencies.KotlinScriptResolveScopeProvider"/>
     <projectOpenProcessor implementation="org.jetbrains.kotlin.gradle.GradleKotlinDSLProjectOpenProcessor"/>
+    <projectImportProvider implementation="org.jetbrains.kotlin.gradle.GradleKotlinDSLProjectImportProvider"/>
 
   </extensions>