Use information about receivers in completion

- Found few problems during resolving a single functon; disabled
assertions and marked them with TODO
- Add simple completion tests to simplify development

idea/idea-completion/testData/basic/common/primitiveCompletion/explicitReceiverCompletion.kt

@@ -0,0 +1,13 @@
+class A {
+    fun aa() {}
+    val aaa = 10
+}
+
+fun test() {
+    val a = A()
+
+    a.<caret>
+}
+
+// EXIST: aa
+// EXIST: aaa