Completion: fixed filtering shadowed declarations for generic functions

idea/idea-completion/testData/basic/multifile/MoreSpecificExtensionGeneric/MoreSpecificExtensionGeneric.dependency.kt

@@ -0,0 +1,7 @@
+package dependency
+
+interface Iterable<T>
+interface List<T> : Iterable<T>
+
+fun <T> List<T>.xxx(t: T){}
+fun <T> Iterable<T>.xxx(t: T){}

idea/idea-completion/testData/basic/multifile/MoreSpecificExtensionGeneric/MoreSpecificExtensionGeneric.kt

@@ -0,0 +1,6 @@
+fun foo(list: dependency.List<Int>) {
+    list.xx<caret>
+}
+
+// EXIST: { lookupString: "xxx", itemText: "xxx", tailText: "(t: Int) for List<T> in dependency", typeText: "Unit" }
+// NOTHING_ELSE