chore: move the go code into a subfolder

apps/api/internal/cache/connector/pg/set.sql

@@ -0,0 +1,19 @@
+with object as (
+	insert into cache.objects (cache_name, payload)
+	values ($1, $3)
+	returning id
+)
+insert into cache.string_keys (
+	cache_name,
+	index_id,
+	index_key,
+	object_id
+)
+select $1, keys.index_id, keys.index_key, id as object_id
+from object, jsonb_to_recordset($2) keys (
+	index_id bigint,
+	index_key text
+)
+on conflict (cache_name, index_id, index_key) do
+	update set object_id = EXCLUDED.object_id
+;