Fix the problem with code completion of type extension method

KT-23834 Fixed

idea/idea-completion/testData/basic/common/shadowing/ExtensionShadows.kt

@@ -0,0 +1,13 @@
+class Shadow {
+    fun shade() {}
+}
+
+fun <X> Shadow.shade() {}
+
+fun context() {
+    Shadow().sha<caret>
+}
+
+// EXIST: { lookupString: "shade", itemText: "shade", tailText: "()", typeText: "Unit" }
+// EXIST: { lookupString: "shade", itemText: "shade", tailText: "() for Shadow in <root>", typeText: "Unit" }
+// NOTHING_ELSE

idea/idea-completion/testData/basic/common/shadowing/PreferMoreSpecificExtensionGenericWithMultipleParam.kt

@@ -0,0 +1,9 @@
+fun <T, S> List<T>.xxx(t: T){}
+fun <T, W> Iterable<T>.xxx(t: T){}
+
+fun foo() {
+    listOf(1).xx<caret>
+}
+
+// EXIST: { lookupString: "xxx", itemText: "xxx", tailText: "(t: Int) for List<T> in <root>", typeText: "Unit" }
+// NOTHING_ELSE