Fix double quotes in diagnostic messages

For diagnostics without any parameters, the given text is simply rendered as a
String, so no symbols should be escaped.

For diagnostics with parameters, the format in java.text.MessageFormat is used,
so one single quote is erased and two single quotes become one single quote in
the rendered text.

jps-plugin/testData/incremental/classHierarchyAffected/enumEntryAdded/build.log

@@ -26,7 +26,7 @@ End of files
 Exit code: ABORT
 ------------------------------------------
 COMPILATION FAILED
-when expression must be exhaustive, add necessary 'C' branch or 'else' branch instead
+'when' expression must be exhaustive, add necessary 'C' branch or 'else' branch instead
 
 ================ Step #2 =================