Implement common Throwable.addSuppressed/suppressed extensions

Instead of `suppressed` Array we provide `suppressedExceptions` List

#KT-23737

libraries/stdlib/common/src/kotlin/ExceptionsH.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2018 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
@@ -115,4 +115,23 @@ internal class KotlinNothingValueException : RuntimeException {
     constructor(message: String?) : super(message)
     constructor(message: String?, cause: Throwable?) : super(message, cause)
     constructor(cause: Throwable?) : super(cause)
-}
+}
+
+
+/**
+ * When supported by the platform, adds the specified exception to the list of exceptions that were
+ * suppressed in order to deliver this exception.
+ */
+@SinceKotlin("1.4")
+public expect fun Throwable.addSuppressed(exception: Throwable)
+
+/**
+ * Returns a list of all exceptions that were suppressed in order to deliver this exception.
+ *
+ * The list can be empty:
+ * - if no exceptions were suppressed;
+ * - if the platform doesn't support suppressed exceptions;
+ * - if this [Throwable] instance has disabled the suppression.
+ */
+@SinceKotlin("1.4")
+public expect val Throwable.suppressedExceptions: List<Throwable>