Add instance name as parameter to various CLI commands

Currently, only the "trove show" command will take instance-ID or
instance-name as its parameter. There are many more commands in the
CLI that require an instance reference as a parameter but require that
the instance-ID be used. It would be helpful to customers to be able
to use instance-ID or instance-name interchangeably throughtout the CLI.

Spec: https://review.openstack.org/#/c/136424/