load views as a SQL file and rename to 'secondary importance'

The only requirement for secondary importance is that a raster table
comes out of it. The generic name leaves open where the data comes
from.

nominatim/clicmd/args.py

@@ -115,7 +115,7 @@ class NominatimArgs:
     address_levels: bool
     functions: bool
     wiki_data: bool
-    osm_views: bool
+    secondary_importance: bool
     importance: bool
     website: bool
     diffs: bool