Created module idea-test-framework and moved classes needed for idea tests there

Moved tests for completion and their test data into module idea-completion

idea/idea-completion/testData/basic/common/SmartCastAfterIf.kt

@@ -0,0 +1,14 @@
+trait Expr
+class Num(val value : Int) : Expr
+
+fun eval(e : Expr) {
+    if (e is Num) {
+        return e.<caret>
+    }
+}
+
+// EXIST: value
+
+
+
+