Changing from specific method (e.g: vPOST) to generic method (e.g: GET) on the…

See merge request mec/MEC-tests!2

Camel-case HTTP status codes

See merge request mec/MEC-tests!1

Changing from specific method (e.g: vPOST) to generic method (e.g: GET) on the invalid behaviours, regarding failed authentications

- Set any_value for data structures

- Replace HTTP status codes with literals
- Folder structure follows the TSS
- Message body details relevant fields