Invalid bulk operation fails alone

[azmeuk]

Per RFC 7644 §3.7.3, a failed bulk operation is reported in its own result, and the other operations still run. Until now, one invalid operation made the validation of the whole BulkRequest fail.

• In the BULK_REQUEST context, each operation is validated on its own. An invalid operation becomes a BulkOperation with a status and an Error in response. It keeps its method, bulkId and path when they are readable.
• An envelope that is not valid still fails the whole request, for example when Operations is not a list or failOnErrors is invalid.
• Under a ScimProvider, the model of an operation comes from the endpoint in its path.
• Without a provider, the model is still picked from the union of the type parameter.
• BulkOperation gains the endpoint and resource_id properties.