Replace recruitment status values with constants

[robines]

Ref: #1212 (comment)

So instead of

 recruitmentApplicant.recruiter_status == 0 &&

We should have something like

 recruitmentApplicant.recruiter_status == RECRUITMENT_STATUS_NOT_SET &&

Constants are already defined in backend, need to bring them to the frontend:

class RecruitmentPriorityChoices(models.IntegerChoices):
    NOT_SET = 0, _('Not Set')
    RESERVE = 1, _('Reserve')
    WANTED = 2, _('Wanted')
    NOT_WANTED = 3, _('Not Wanted')


class RecruitmentStatusChoices(models.IntegerChoices):
    NOT_SET = 0, _('Not Set')
    CALLED_AND_ACCEPTED = 1, _('Called and Accepted')
    CALLED_AND_REJECTED = 2, _('Called and Rejected')
    REJECTION = 3, _('Rejection')
    AUTOMATIC_REJECTION = 4, _('Automatic Rejection')