IR: unify 3 copies of function body remapping

Also,

  1. remove some redundant copies;

  2. fix remapping of non-local returns in lambdas if the body is moved
     after LocalDeclarationsLowering (the lambda is no longer inside the
     body, but must still be visited)

compiler/testData/codegen/boxInline/nonLocalReturns/fromInterfaceDefaultGetter.kt

@@ -0,0 +1,16 @@
+// FILE: 1.kt
+package test
+
+inline fun myRun(f: () -> Nothing): Nothing = f()
+
+// FILE: 2.kt
+import test.*
+
+interface I {
+    val ok: String
+        get() { myRun { return "OK" } }
+}
+
+class C : I
+
+fun box(): String = C().ok