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/Enum.kt

@@ -0,0 +1,8 @@
+package test
+
+fun checkEnum(e: Enum) = when(e) {
+	Enum.SOUTH -> println(1)
+	Enum.NORTH -> println(2)
+	Enum.WEST -> println(3)
+	Enum.EAST -> println(42)
+}