Create company employee.

This endpoint allows you to create a new employee in the system.
The request body must include the minimum required fields: email, firstName, surname, and the work object with site and startDate.
While not all fields are mandatory, we recommend populating as many fields as possible to ensure complete employee records from the start.
Specifically, it's recommended to include work.department and work.title.
You can include any additional fields from the Fields Metadata API to enrich the employee's profile during creation.