Generate synthetic functions for local functions with default values, by

re-ordering the lowering phases.

The changes in InterfaceLowering are necessary so that IrElements that
target the removed functions are re-targeted to the new functions in
DefaultImpls. This affects local functions in interface functions since
now LocalDeclarationsLowering comes before InterfaceLowering.

compiler/testData/codegen/box/functions/localFunctions/kt3978.kt

@@ -1,11 +1,10 @@
-// IGNORE_BACKEND: JVM_IR
 fun box() : String {
-
-
     fun local(i: Int = 1) : Int {
         return i
     }
 
-    return if (local() != 1) "fail" else "OK"
-}
+    if (local() != 1) return "Fail 1"
+    if (local(2) != 2) return "Fail 2"
 
+    return "OK"
+}