Add Template Options Based on Category

It would be cool if we added different templates for submitting a job. Basically, we could display a different template based on the job category the employer chooses when they want to submit a listing. And the admin would set the templates for each category in the admin.

This would be a nice feature since not all listings need the same fields and this would give them a bit more flexibility.

Came up in 3184385-t

Review the existing job-submission flow and the admin category settings to find the relevant entry points for template selection and configuration. Define how each category maps to a configurable template, then verify the behavior for employers submitting listings and administrators managing templates.

Written by the indexing model from the issue text.