lock times for consultation blocks, fixes #1264

app/controllers/consultation/admin.php

app/views/consultation/admin/create.php

app/views/consultation/admin/edit.php

app/views/consultation/admin/index.php

app/views/consultation/admin/ungrouped.php

app/views/consultation/block-description.php

app/views/consultation/block-locked.php

app/views/consultation/overview/index.php

app/views/consultation/overview/ungrouped.php

app/views/consultation/slot-occupation.php

db/migrations/5.3.6_add_consultation_lock_time.php

lib/classes/JsonApi/Routes/Consultations/BookingsCreate.php

lib/classes/JsonApi/Schemas/ConsultationBlock.php

lib/classes/JsonApi/Schemas/ConsultationSlot.php

lib/models/ConsultationBlock.php

lib/models/ConsultationSlot.php

resources/assets/stylesheets/scss/consultation.scss

tests/jsonapi/ConsultationHelper.php

tests/jsonapi/ConsultationsBookingCreateBySlotIndexTest.php

tests/jsonapi/ConsultationsBookingCreateTest.php