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/AbstractClass.txt

@@ -0,0 +1,11 @@
+package test
+
+public abstract class AbstractClass {
+    public constructor AbstractClass()
+    public abstract fun implementMe(): kotlin.Unit
+}
+
+public final class AbstractClassImpl : test.AbstractClass {
+    public constructor AbstractClassImpl()
+    public open fun implementMe(): kotlin.Unit
+}