Add remaining hook handlers [goopstest]

[gruyaume]

Enhancement Proposal

Goopstest currently covers most features offered by Goops, but not all of it. The goal of this task is to get 100% parity between Goops features and Goopstest. We should add goopstest support for the following hooks:

• credential-get: feat: add missing handlers for credential-get, goal-state, reboot, resource [goopstest] #71
• goal-state: feat: add missing handlers for credential-get, goal-state, reboot, resource [goopstest] #71
• juju-reboot: feat: add missing handlers for credential-get, goal-state, reboot, resource [goopstest] #71
• resource-get: feat: add missing handlers for credential-get, goal-state, reboot, resource [goopstest] #71
• network-get
• storage-add
• storage-get
• storage-list
• unit-get