Rename generic layer.sql to actual_layer_name .sql (#1034)

Following layers had generic `layer.sql` name.

- `aerodrome_label`
- `aeroway`
- `housenumber`
- `mountain_peak`
- `park`
- `place`
- `poi`
- `transportation`
- `transportation_name`
- `water_name`

This PR renames `layer.sql` to `aerodrome_label.sql`, `aeroway.sql`...

layers/aerodrome_label/aerodrome_label.sql

@@ -0,0 +1,43 @@
+
+-- etldoc: layer_aerodrome_label[shape=record fillcolor=lightpink, style="rounded,filled", label="layer_aerodrome_label | <z10_> z10+" ] ;
+
+CREATE OR REPLACE FUNCTION layer_aerodrome_label(bbox geometry,
+                                                 zoom_level integer)
+    RETURNS TABLE
+            (
+                osm_id   bigint,
+                geometry geometry,
+                name     text,
+                name_en  text,
+                name_de  text,
+                tags     hstore,
+                class    text,
+                iata     text,
+                icao     text,
+                ele      int,
+                ele_ft   int
+            )
+AS
+$$
+SELECT
+    -- etldoc: osm_aerodrome_label_point -> layer_aerodrome_label:z10_
+    osm_id,
+    geometry,
+    name,
+    COALESCE(NULLIF(name_en, ''), name) AS name_en,
+    COALESCE(NULLIF(name_de, ''), name, name_en) AS name_de,
+    tags,
+    CASE
+        %%FIELD_MAPPING: class %%
+        ELSE 'other'
+        END AS class,
+    NULLIF(iata, '') AS iata,
+    NULLIF(icao, '') AS icao,
+    substring(ele FROM E'^(-?\\d+)(\\D|$)')::int AS ele,
+    round(substring(ele FROM E'^(-?\\d+)(\\D|$)')::int * 3.2808399)::int AS ele_ft
+FROM osm_aerodrome_label_point
+WHERE geometry && bbox
+  AND zoom_level >= 10;
+$$ LANGUAGE SQL STABLE
+                -- STRICT
+                PARALLEL SAFE;