Enhancement: Add support to perform rolling upgrades for shc and idx

[zyphermonkey]

Splunk has documentation on how to successfully perform rolling upgrades for both the search and indexing tiers.

Would it be possible to implement these into the splunk_upgrade_full_stack.yml, upgrade_splunk.yml, or potentially a brand new playbook/tasks file?

Splunk Documentation

https://docs.splunk.com/Documentation/Splunk/8.2.2/DistSearch/SHCrollingupgrade
https://docs.splunk.com/Documentation/Splunk/8.2.2/Indexer/Searchablerollingupgrade