JetDiagnosticsTest migrated to TestGenerator

- test data files renamed from *.jet to *.kt

compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2226.kt

@@ -0,0 +1,15 @@
+//KT-2226 Parameter used as delegation by object marked as unused
+package a
+
+trait A {
+    fun foo() : Int
+}
+
+class B : A {
+    override fun foo() = 10
+}
+fun foo(b: B) : Int {
+    val o = object : A by b {
+    }
+    return o.foo()
+}