Move to new modular layer structure

layers/building/building.yaml

@@ -0,0 +1,12 @@
+layer:
+  id: "building"
+  description: Roads
+  buffer_size: 4
+  datasource:
+    query: (SELECT * FROM layer_building(!bbox!, z(!scale_denominator!))) AS t
+  fields:
+    admin_level: Number
+    class: String
+    scalerank: Number
+schema:
+  - ./building.sql