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/LocalMultideclarationValues.kt

@@ -0,0 +1,10 @@
+data class TestData(val first: Int, val second: String)
+
+fun f() : TestData = TestData(42, "Second")
+
+fun test() {
+  val (dataFirst, dataSecond) = f()
+  d<caret>
+}
+
+// EXIST: dataFirst, dataSecond