Introduce experimental -Xuse-javac compilation mode

In this mode, javac AST and Symbol files are used during
Kotlin compilation instead of PSI / binary stuff.
Later, they are reused for Java file compilation.
javac in this mode is integrated into kotlinc.

compiler/testData/compileKotlinAgainstJava/InnerClass.txt

@@ -0,0 +1,12 @@
+package test
+
+public fun useInnerClass(): kotlin.Unit
+
+public open class InnerClass {
+    public constructor InnerClass()
+
+    public/*package*/ open inner class Inner {
+        public/*package*/ constructor Inner()
+        public open fun doNothing(): kotlin.Unit
+    }
+}