Impelmented the terminal route of the API

[morukele]

Implemented the terminal route of the API, which responds to the following issues:

• Implement fetch terminal #22 Implement fetch terminal
• Implement fetch event status #19 Implement fetch event status
• Implement fetch terminal status #20 Implement fetch terminal status
• Implement list terminals #21 Implement list terminals
• Implement update terminal #23 Implement update terminal
• Implement commission terminal #24 Implement commission terminal
• Implement decommission terminal #25 Implement decommission terminal

The next step is to test these endpoints, which is difficult because of the lack of access to a terminal device.