[TEST] Add core of new tests infrastructure

It contains different abstractions which represents parts of compiler
  pipeline and artifacts produced by them, service structure, handlers
  for analysis of artifacts

compiler/test-infrastructure-utils/tests/org/jetbrains/kotlin/test/util/StringUtils.kt

@@ -0,0 +1,9 @@
+/*
+ * 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.
+ */
+
+package org.jetbrains.kotlin.test.util
+
+fun Iterable<*>.joinToArrayString(): String = joinToString(separator = ", ", prefix = "[", postfix = "]")
+fun Array<*>.joinToArrayString(): String = joinToString(separator = ", ", prefix = "[", postfix = "]")