Add gutter icon with navigation to related files for Android components

idea/testData/android/gutterIcon/relatedFiles.kt

@@ -0,0 +1,9 @@
+import android.app.Activity
+import android.os.Bundle
+
+class <caret>KotlinActivity : Activity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_kotlin)
+    }
+}