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/Inheritance.txt

@@ -0,0 +1,28 @@
+package test
+
+public/*package*/ abstract class AbstractInheritance : test.Interface {
+    public/*package*/ constructor AbstractInheritance()
+    public open fun getAnswer(): kotlin.Int
+}
+
+public/*package*/ interface I {
+    public abstract fun getAnswer(): kotlin.Int
+}
+
+public/*package*/ interface I2 : test.I {
+    public abstract fun getAnswer(): kotlin.Int
+}
+
+public open class Inheritance : test.AbstractInheritance {
+    public constructor Inheritance()
+    public open /*fake_override*/ fun getAnswer(): kotlin.Int
+}
+
+public final class InheritanceImpl : test.Inheritance, test.I2 {
+    public constructor InheritanceImpl()
+    public open /*fake_override*/ fun getAnswer(): kotlin.Int
+}
+
+public/*package*/ interface Interface : test.I {
+    public abstract fun getAnswer(): kotlin.Int
+}