Send compiler output to stderr instead of stdout

Test only stderr in kotlinc test now and move the '-script' test to integration
tests where both stdout and stderr is tested

compiler/integration-tests/testData/compilationFailed/hello.compile.expected

@@ -1,7 +1,6 @@
-OUT:
-ERROR: [TestData]/hello.kt: (4, 5) Unresolved reference: a
 
 ERR:
+ERROR: [TestData]/hello.kt: (4, 5) Unresolved reference: a
 exec() finished with COMPILATION_ERROR return code
 
 Return code: 1

compiler/integration-tests/testData/simpleScript/script.expected

@@ -0,0 +1,5 @@
+OUT:
+hi
+there
+
+Return code: 0

compiler/integration-tests/testData/simpleScript/script.kts

@@ -0,0 +1,3 @@
+for (arg in args) {
+    println(arg)
+}

compiler/integration-tests/testData/syntaxErrors/test.compile.expected

@@ -1,7 +1,6 @@
-OUT:
-ERROR: [TestData]/test.kt: (4, 20) Expecting an element
 
 ERR:
+ERROR: [TestData]/test.kt: (4, 20) Expecting an element
 exec() finished with COMPILATION_ERROR return code
 
 Return code: 1