test cases in test_routes.py expect a validation error format thats need to be match fastjsonschema provides

{key} is a required property for missing required fields
Additionnal properties are not allowed for extra properties

Modifications :
- Catch fastjsonjsonschema exceptions and extract the field name
- transform the error message to match the format expected by tests
- uses string manipulations to handle both mising required fields and additionnal properties cases

pytest : 40/40 passed

 enlevé

…ions/OpenGeodeWeb-Back into fix/fast_json_schema

…refact