preserve comments: concatenation to message format

compose tests into one

java/java-tests/testData/codeInsight/concatenationToMessageFormat/comments.java

@@ -0,0 +1,10 @@
+class Simple {
+
+  void f(String a, String b) {
+    String s = "a:" +//a before arg
+               a <caret>+ //comment
+               "b:"//after literal
+               + /*before arg*/b; //end comment
+
+  }
+}