Support fetching ionosonde data for FoF2 and MUF display on the Conditions page

data/solar_conditions.py

@@ -161,6 +161,8 @@ class SolarConditions:
     blackout_forecast_r1r2: dict = None
     # NOAA Radio Blackout (R3 or greater) probability forecast, keyed by UNIX timestamp of start of day UTC
     blackout_forecast_r3_or_greater: dict = None
+    # Ionosonde measurements from LGDC, list of dicts with keys: ursi, name, fof2, muf
+    ionosonde_data: list = None
 
     # Derived values (populated by infer_descriptions())
     # HF radio blackout risk description, derived from xray