Copy KotlinSignature to package "kotlin.jvm"

Support both KotlinSignature classes in the compiler and in the IDEA plugin.
The old one will be deprecated later and dropped eventually

core/runtime.jvm/src/kotlin/jvm/KotlinSignature.java

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2010-2014 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package kotlin.jvm;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Target;
+
+@Target({ElementType.METHOD, ElementType.TYPE, ElementType.CONSTRUCTOR, ElementType.FIELD})
+public @interface KotlinSignature {
+    String value();
+}