Support WITH_UNSIGNED kind in diagnostics tests, add tests

compiler/tests-common/tests/org/jetbrains/kotlin/checkers/AbstractDiagnosticsWithUnsignedTypes.kt

@@ -0,0 +1,14 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.checkers
+
+import org.jetbrains.kotlin.test.ConfigurationKind
+
+abstract class AbstractDiagnosticsWithUnsignedTypes : AbstractDiagnosticsTest() {
+    override fun getConfigurationKind(): ConfigurationKind {
+        return ConfigurationKind.WITH_UNSIGNED_TYPES
+    }
+}