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/DefaultModifier.txt

@@ -0,0 +1,12 @@
+package test
+
+public fun useDefaultMethod(): kotlin.String!
+
+public open class DefaultModifier : test.WithDefault {
+    public constructor DefaultModifier()
+    public open /*fake_override*/ fun getString(): kotlin.String!
+}
+
+public/*package*/ interface WithDefault {
+    public open fun getString(): kotlin.String!
+}