Add UI for custom data handling, ImportJob class selection

app/controllers/assignments_controller.rb

app/controllers/candidates_controller.rb

app/controllers/conferences_controller.rb

app/controllers/sessions_controller.rb

app/javascript/controllers/conference_form_controller.js

app/jobs/pretalx/import_job.rb

app/jobs/republica_2023_or_later/import_job.rb

app/models/assignment.rb

app/models/conference.rb

app/subscribers/telegram_bot_subscriber.rb

app/views/conferences/edit.html.erb

app/views/conferences/index.html.erb

app/views/conferences/new.html.erb

app/views/conferences/show.html.erb

config/initializers/filter_parameter_logging.rb

config/queue.yml

config/routes.rb