Back to png icons in Android Studio

It's not support 16px @2x.svg icons yet, we need to wait for AS 3.4

#KT-29533 Fixed

compiler/psi/src/org/jetbrains/kotlin/idea/KotlinFileIcon.java.as33

@@ -0,0 +1,14 @@
+/*
+ * Copyright 2010-2019 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 org.jetbrains.kotlin.idea;
+
+import com.intellij.openapi.util.IconLoader;
+
+import javax.swing.*;
+
+public interface KotlinFileIcon {
+    Icon KOTLIN_FILE = IconLoader.getIcon("/org/jetbrains/kotlin/idea/icons/kotlin_file.png");
+}

idea/idea-analysis/src/org/jetbrains/kotlin/idea/IconExtensionChooser.java.as33

@@ -0,0 +1,12 @@
+/*
+ * Copyright 2010-2019 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 org.jetbrains.kotlin.idea;
+
+public interface IconExtensionChooser {
+    static String iconExtension() {
+        return "png";
+    }
+}