Improve options for Job Posting Remote/Hybrid/On-Site

### Describe the solution you'd like
Instead of just a checkbox for Remote Position, drop down for Remote, Hybrid, On-Site as those options are becoming more common.

### Describe alternatives you've considered
Using field editor plugin to add the option.

Trace the existing Remote Position checkbox through the job submission and WordPress admin field definitions; the issue does not name specific files or tests. Check how the current value is stored and displayed, then verify that Remote, Hybrid, and On-Site can be selected wherever the existing option is supported.

Written by the indexing model from the issue text.