Extract Function: Do not suggest "unit" as function name

#KT-6402 Fixed

idea/testData/refactoring/extractFunction/parameters/misc/qualifiedPackage.kt.after

@@ -6,11 +6,11 @@ fun foo() = 1
 // SIBLING:
 class MyClass {
     fun test() {
-        unit()
+        __dummyTestFun__()
     }
 }
 
-private fun unit() {
+private fun __dummyTestFun__() {
     foo()
     a
 }