Fixed is not able to set lower number of sick day than is already taken
Fixed a taking vacation for the same day.
Cannot take a vacation in past, refactor VacationDay to Vacation in domain package
Messages
Handle different or non inputs, unit tests, error messages
Documentation domain and dto, unit test domain, error input domain
Re #7477 Edited endpoints and created mock manager for data
Re #7386 Implemented APIs endpoints with DTOs