Improve testing for FBFM40's seasonal LFPS integration.

[lindsaywiard]

While implementing latest-year LFPS support for LANDFIRE fuel models, I was thinking about confirming the API's coverage check (validate_lfps_coverage) actually reaches LFPS successfully for an API request that requires LFPS. Working on that, I realized the seasonal FBFM40 was missing this. Its LFPS coverage check is a live call to LFPS's product catalog, made synchronously by the API itself before a grid is created, the same way 3DEP's coverage check works. 3DEP tests live against a domain with known coverage (test_documented_examples_are_accepted in test_3dep.py), so I thought seasonal should be tested the same way.

During the latest-year fuel model implementation in Griddle, I also noticed we had no way to know if our configured seasonal version stops being served by LFPS. We will need to update the code base when LANDFIRE move to a new base vintage, so this test can act as a reminder to check.

Changes

• services/api/tests/fixtures.py

  • Add a factory to load a domain fixture file into Firestore-ready test data
  • Lets us reuse the domain fixture files already saved in shared_data

• services/api/tests/conftest.py

  • Add lfps_covered_domain, loading threedep_ept_seam.json via that factory
  • We've verified this domain has coverage across all seasonal fuels windows
  • This fixture will also be useful for testing the latest-year (annual) LFPS path because it is in the SW region, which is released first for a new annual version

• services/api/api/resources/grids/fbfm40/examples.py

  • Split the documented examples into staged-data and LFPS-sourced groups
  • The LFPS-sourced examples can be tested against the covered SW region domain
  • Change the seasonal example's season from SP to ES because ES is updated first

• services/api/tests/resources/grids/fbfm40/test_router.py:

  • add a live-coverage test that posts the LFPS-sourced example against lfps_covered_domain
  • confirms the LFPS coverage check succeeds

• services/griddle/tests/integration/test_landfire_lfps.py

  • add a test that fails once our configured seasonal version is no longer live in LFPS's catalog
  • will notify us when we need to update the version for the seasonal fuels