rename sql directory to lib-sql

Also introduces a separate constant for the sql directory, so that
it can be put separately from the rest of the data if required.

lib-sql/indices_updates.src.sql

@@ -0,0 +1,9 @@
+-- Indices used only during search and update.
+-- These indices are created only after the indexing process is done.
+
+CREATE INDEX CONCURRENTLY idx_placex_pendingsector ON placex USING BTREE (rank_address,geometry_sector) {ts:address-index} where indexed_status > 0;
+
+CREATE INDEX CONCURRENTLY idx_location_area_country_place_id ON location_area_country USING BTREE (place_id) {ts:address-index};
+
+DROP INDEX CONCURRENTLY IF EXISTS place_id_idx;
+CREATE UNIQUE INDEX CONCURRENTLY idx_place_osm_unique on place using btree(osm_id,osm_type,class,type) {ts:address-index};