todo: positions in editEmployee?

Added a deprecated tag to old method. Added a check to add and edit shift that sees if there are any conflicts with an approved time off. Added the same checks from add shift to edit shift. Added methods for addShiftIgnore and editShiftIgnore.

Changed the startDate and endDate to LocalDate for easier evaluation and integration. Added a conflictsWithTimeOff method that checks if a date conflicts with a time off, note this doesn't check if it's been approved though.