Record btc utxo in cashierdb

sql/cashier.sql

@@ -4,6 +4,15 @@ CREATE TABLE IF NOT EXISTS deposit_keypairs(
     coin_key_public BLOB NOT NULL,
 	asset_id BLOB NOT NULL
 );
+PRAGMA foreign_keys=on;
+CREATE TABLE IF NOT EXISTS btc_utxo(
+    tx_id BLOB PRIMARY KEY NOT NULL,
+    balance INTEGER NOT NULL,
+    btc_key_public BLOB NOT NULL,
+    FOREIGN KEY (btc_key_public)
+        REFERENCES deposit_keypairs (coin_key_public)
+        ON UPDATE CASCADE
+);
 CREATE TABLE IF NOT EXISTS withdraw_keypairs(
     coin_key_id BLOB PRIMARY KEY NOT NULL,
 	d_key_private BLOB NOT NULL,