Made vararg parameters have Array<out T> type

instead of simply Array<T>
  #KT-1638 Fixed
  #KT-2163 Fixed
  #KT-3213 Fixed
  #KT-4172 Fixed
  #KT-5534 Fixed

compiler/testData/diagnostics/tests/varargs/varargsAndOut1.txt

@@ -0,0 +1,5 @@
+package
+
+internal fun </*0*/ T> foo(/*0*/ a: kotlin.Array<T>): kotlin.Array<T>
+internal fun test(/*0*/ vararg a: kotlin.String /*kotlin.Array<out kotlin.String>*/): kotlin.Unit
+internal fun </*0*/ T> test1(/*0*/ vararg t: T /*kotlin.Array<out T>*/): kotlin.Unit