Deprecate maven-shared-utils

As discussed in https://lists.apache.org/thread/9wkmo1cfq7hx6qwo2xp070rkdz1w5myp this library never became successor of plexus-utils and therefore is less maintained. Instead of maintaining two libraries we should deprecated Maven Shared Utils and recommend using plain JDK API where possible or fall back to either plexus-utils or other well known third party libraries.