Added smart priorities for true, false and null into basic completion

idea/idea-completion/testData/weighers/basic/expectedInfo/Null.kt

@@ -0,0 +1,11 @@
+class X
+
+fun f(x: X?){}
+
+fun g(nn: Any, np: X) {
+    f(n<caret>)
+}
+
+// ORDER: np
+// ORDER: null
+// ORDER: nn