Add ansible playbook to clean nodes in inventory

[cailafinn]

Cleans the jenkins workspace stored in docker containers for a set of nodes defined in the inventory.txt file.

Provides tags to determine which of the pipeline's workspaces should be cleaned. Otherwise, does them all.

To Test:

1. Pick a node and run the script against a nightly tag (probably least intrusive since they're always clean), following the instructions in the documentation.

Fixes #103

[warunawickramasingha]

I think it will be useful if there is an additional section to log the directories that would be deleted via this. For example, having some logging tasks that will always run regardless of the tag specified would list the existing directories along with their sizes.

The same can be used to check the existing dirs before deleting as well(By first running without giving any tags).

Suggested change

	- name: Collect existing dir names and their sizes
	community.docker.docker_container_exec:
	container: "{{ agent_name }}"
	command: bash -l -c "du -sh * | awk '{print $1, $2}'"
	chdir: "/jenkins_workdir/workspace"
	register: dirs_and_sizes
	become: yes
	tags: [always]
	- name: Log existing dirs with their sizes
	debug:
	msg: "{{ dirs_and_sizes.stdout_lines }}"
	tags: [always]

[warunawickramasingha]

Requesting a small change to log the directories before cleaning. Otherwise the changes look good.

[warunawickramasingha]

Thanks for the changes, tested this on isis-cloud-linux-b-5 node(made the node temporarily offline) with nightly tag and it worked as expected.

Node is back online now and I am happy to approve!