feat: get the first account created in the service

In order to reproduce the case:

1. connect to a fluid in the application
2. in the cozy home, add a account on the same konnector
3. modify the access_token of the last account using postman

Expected result:

• Ensure that the application have a good behaviour in the consumption screen.
• Refresh should works propertly with the right account/trigger
• Deletion of konnector should delete all linked accounts and triggers