Support deployment via Ansible

[pdbossman]

Ansible playbook to support deploying scylla-migrator. Includes convenience scripts to set environment variables, start/stop spark master and slaves, as well as spark-submit jobs.

Limitations:

• The ansible playbook was designed and tested with Ubuntu 22.04.

[pdbossman]

@tarzanek see the commits submitted to address review comments. I've also updated the readme to more thoroughly describe the process.

[tarzanek]

thank you, this is a good start