Add the ability to rename a node after it has already accumulated data

We currently use ansible_fqdn in the playbook that automates the addition of nodes to PMM. This poses a few issues:

• the hostname may have no resemblance to the CNS entry -> confusion
• the hostname cannot be resolved by ansible -> localhost.localdomain -> confusion
• the customer wants the host labelled differently

Currently there is only the option to remove and add back the node with a different name, thus losing visibility of the already accumulated data.

Adding pmm-admin rename <existing name> <new name> or similar would allow the Consul and QAN data to be "fixed". Loss of Prometheus data would need to be accepted in such a use-case

Before renaming : re-check if User ready to rename and lost previous data on Graph (Y/n) and --force-rename option to rename without asking confirmation