Bug 9060: Karaf CLI command to print open transactions

Bug 9060: Karaf CLI command to print open transactions

This is not a 1:1 cherry-pick from master, but includes manual work to:
  1. fix versions and more in mdsal-trace/cli/pom.xml
  2. rework PrintOpenTransactionsCommand.java from Karaf 4 API to v3
  3. incl. for ^^^ a new BP commands.xml (not needed anymore on Karaf 4)
  4. features-mdsal-trace POM and features.xml include new cli bundle

including some minor changes to make output more pretty / readable.

This is, for now, the last in a serious of commits which is part of a
solution I'm proposing in order to be able to detect OOM issues such as
Bug 9034, based on using the mdsal-trace DataBroker.

Change-Id: I83af00a0713be4e8fab3085942b7b57d7183a20c
Signed-off-by: Michael Vorburger <vorburger@redhat.com>