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/handlers/TabReplaceThis.kt

@@ -0,0 +1,5 @@
+fun foo(s: String){ }
+
+fun String.bar(sss: String) {
+    foo(<caret>this)
+}