Fix misleading `getDesiredResourceTags` behavior
https://github.com/aws-cloudformation/cloudformation-cli-java-plugin/blob/75133adfd5b82c347bf31579b09e82750b47cde7/src/main/java/software/amazon/cloudformation/AbstractWrapper.java#L536-L549
Here we claim getDesiredResourceTags return User-defined tags. Intuitively readers would assume it's for user tags only.
However, I have noticed system tags such as aws:cloudformation:stackid is being added in the returned results while testing my CFN stack. Given we already have request.getRequestData().getSystemTags() method for system tags, please consider to either update the code comments explaining why these non User-defined tags are here, or provide another method that will only return user tags to avoid confusions.