Use go embed to load queries from static files (#607)

pkg/statements/sql/table_constraints.sql

@@ -0,0 +1,14 @@
+SELECT
+  conname AS name,
+  pg_get_constraintdef(c.oid, true) AS definition
+FROM
+  pg_constraint c
+JOIN
+  pg_namespace n ON n.oid = c.connamespace
+JOIN
+  pg_class cl ON cl.oid = c.conrelid
+WHERE
+  n.nspname = $1
+  AND relname = $2
+ORDER BY
+  contype DESC