KT-688: Show kotlin keywords as auto completion in IDEA

idea/testData/completion/keywords/InFunctionScope.kt

@@ -0,0 +1,5 @@
+fun foo() {
+    <caret>
+}
+
+// EXIST: val, var

idea/testData/completion/keywords/InTypeScope.kt

@@ -0,0 +1,6 @@
+fun foo() {
+    val test : <caret>
+}
+
+// TODO: Move all keywords to absent
+// EXPECT: fun, val, var, namespace

idea/testData/completion/keywords/TopScope.kt

@@ -0,0 +1,8 @@
+<caret>
+
+// EXPECT: namespace, as, type, class, this, super, val, var, fun, for, null, true
+// EXPECT: false, is, in, throw, return, break, continue, object, if, try, else, while
+// EXPECT: do, when, trait, This
+// EXPECT: import, where, by, get, set, abstract, enum, open, annotation, override, private
+// EXPECT: public, internal, protected, catch, out, vararg, inline, finally, final, ref
+// ABSENT: ?in, new, extends, implements