NOOP: Format all layer's SQL code (#917)

I would like to reformat all of our SQL to have a concise coding style.
This makes it far easier to understand the code for a casual contributor,
and lets us spot errors more easily.

Most importantly, it makes it much easier to grep (search) the code because it is more likely to be in the same syntax

Some key changes:
* SQL keywords are always UPPERCASE, e.g. `SELECT WHEN AS END ...`
* types, variables, aliases, and field names (identifiers) are always lower case
* `LANGUAGE 'plpgsql'` is now `LANGUAGE plpgsql` (no quotes)
* a few minor spacing/semicolon cleanups

P.S. Per @TomPohys request, `TABLE` is spelled using upper case despite being a type for consistency with PG Docs. Same for `LANGUAGE SQL` vs `LANGUAGE plpgsql`.

layers/housenumber/layer.sql

@@ -1,12 +1,22 @@
-
 -- etldoc: layer_housenumber[shape=record fillcolor=lightpink, style="rounded,filled",
 -- etldoc:     label="layer_housenumber | <z14_> z14+" ] ;
 
 CREATE OR REPLACE FUNCTION layer_housenumber(bbox geometry, zoom_level integer)
-RETURNS TABLE(osm_id bigint, geometry geometry, housenumber text) AS $$
-   -- etldoc: osm_housenumber_point -> layer_housenumber:z14_
-    SELECT osm_id, geometry, housenumber FROM osm_housenumber_point
-    WHERE zoom_level >= 14 AND geometry && bbox;
+    RETURNS TABLE
+            (
+                osm_id      bigint,
+                geometry    geometry,
+                housenumber text
+            )
+AS
 $$
-LANGUAGE SQL
-IMMUTABLE PARALLEL SAFE;
+SELECT
+    -- etldoc: osm_housenumber_point -> layer_housenumber:z14_
+    osm_id,
+    geometry,
+    housenumber
+FROM osm_housenumber_point
+WHERE zoom_level >= 14
+  AND geometry && bbox;
+$$ LANGUAGE SQL IMMUTABLE
+                PARALLEL SAFE;