TxSel integrated with L2DB, Add L1CoordTx creation

- GetL2TxSelection & GetL1L2TxSelection integrated with dbs
- Create L1CoordinatorTx of type CreateAccountDeposit when a L2
requires it (and the AccountCreationAuth exists)

test/l2db.go

@@ -0,0 +1,13 @@
+package test
+
+import "github.com/jmoiron/sqlx"
+
+// CleanL2DB deletes 'tx_pool' and 'account_creation_auth' from the given DB
+func CleanL2DB(db *sqlx.DB) {
+	if _, err := db.Exec("DELETE FROM tx_pool"); err != nil {
+		panic(err)
+	}
+	if _, err := db.Exec("DELETE FROM account_creation_auth"); err != nil {
+		panic(err)
+	}
+}