FAL-1941 Update publication date ranges for filters/aggs
As per client request.
Also refactor so that PUB_DATE_RANGES is the sole source of truth for the ranges.
Test instructions:
- install this and run the frontend app
- add some courses and update the publication date in the search admin metadata - include dates within a month, within 6 months, and within 1 year.
- view the frontend and verify that the required publication date ranges are shown in the filters. See client doc for requirements - also quoted here: 'change the publication options from "past year, past month, past week" to "past year, past six months, past month"'
- run some searches and verify that the expected results are returned for the 3 different date range filters.
Reviewers:
Edited by Ghost User