Convert lambda to reference: handle named arguments more precisely

For trailing lambda intention inserts parameter names for all arguments
if at least one argument used default value.
Otherwise it just keeps existing named arguments.

So #KT-20349 Fixed

idea/testData/intentions/convertLambdaToReference/defaultUnnamed2.kt

@@ -0,0 +1,7 @@
+class Transformer {
+    fun transform(x: Int = 0, y: Int = 1, f: (Int) -> Int) = f(x + y)
+}
+
+fun bar(x: Int) = x * x
+
+val y = Transformer().transform { <caret>bar(it) }