add tests for incremental compilation when only private part changed

Original commit: 62f6cc7f0b

jps/jps-plugin/testData/incremental/pureKotlin/privateMethodAdded/ClassA.kt

@@ -0,0 +1,5 @@
+package test
+
+public class ClassA() {
+    public fun meth1() {}
+}

jps/jps-plugin/testData/incremental/pureKotlin/privateMethodAdded/ClassA.kt.new

@@ -0,0 +1,6 @@
+package test
+
+public class ClassA() {
+    public fun meth1() {}
+    private fun meth2() {}
+}

jps/jps-plugin/testData/incremental/pureKotlin/privateMethodAdded/build.log

@@ -0,0 +1,6 @@
+Cleaning output files:
+out/production/module/test/ClassA.class
+End of files
+Compiling files:
+src/ClassA.kt
+End of files

jps/jps-plugin/testData/incremental/pureKotlin/privateMethodAdded/usage.kt

@@ -0,0 +1,7 @@
+package test
+
+public object Usage {
+    public fun f() {
+        ClassA().meth1()
+    }
+}