Unused import: do not report for 'invoke' function import that is used from same file

#KT-24281 Fixed

idea/testData/quickfix/optimizeImports/invoke2.kt

@@ -0,0 +1,17 @@
+// "Optimize imports" "true"
+// WITH_RUNTIME
+package ppp
+
+import ppp.invoke<caret>
+
+object Bar
+object Foo {
+    // val bar = Bar
+}
+
+fun Foo.bar() = 1
+operator fun Bar.invoke() = 2
+
+fun main() {
+    println(Foo.bar())
+}