Create view for visualisation purposes

\approve @fd @cnievas

migrations/00014_create-view-gde-tiles.sql

+DROP TABLE IF EXISTS public.gde_tiles;
+
+CREATE VIEW public.gde_tiles AS SELECT
+    data_unit_tiles.quadkey AS quadkey,
+    SUM(
+        COALESCE(
+            data_unit_tiles.obm_buildings, 0
+        ) + COALESCE(data_unit_tiles.remainder_buildings, 0)
+    ) AS buildings_total, -- total number of buildings in a tile
+    SUM(
+        COALESCE(data_unit_tiles.obm_buildings, 0)
+    ) AS buildings_available, -- total number of GDE buildings in a tile
+    SUM(
+        COALESCE(data_unit_tiles.remainder_buildings, 0)
+    ) AS buildings_remainder -- total number of remainder buildings in a tile
+FROM data_unit_tiles
+WHERE data_unit_tiles.aggregated_source_id = 1
+GROUP BY data_unit_tiles.quadkey;
+
+ALTER VIEW public.gde_tiles
+OWNER TO postgres;