KT-8623 Completion get in the way when function as declared

#KT-8623 Fixed

idea/idea-completion/testData/handlers/basic/PreferMatchingKeyword.kt

@@ -0,0 +1,9 @@
+fun Any.`as`(s: String): String{}
+
+fun foo(p: Any) {
+    p as<caret>
+}
+
+// INVOCATION_COUNT: 0
+// ELEMENT: *
+// CHAR: ' '