Refactored into service directory

service/migrations/000000_create_messages/up.sql

@@ -0,0 +1,12 @@
+CREATE TABLE IF NOT EXISTS messages (
+  id TEXT PRIMARY KEY NOT NULL,
+  guild_id BIGINT NOT NULL,
+  channel_id BIGINT NOT NULL,
+  user_id BIGINT NOT NULL,
+  created BIGINT NOT NULL,
+  model TEXT NOT NULL,
+  request TEXT NOT NULL,
+  response TEXT NOT NULL,
+  request_tags TEXT[] NOT NULL,
+  response_tags TEXT[] NOT NULL
+);