Add TxID calculation & New{Layer}Tx Type

Add TxID calculation & New{Layer}Tx Type

New{Layer}Tx methods that compute the `TxID` & `TxType` values from the
transaction values:
- NewL1Tx
- NewL2Tx
- NewPoolL2Tx

Add TxID Scanner & Valuer for database/sql

HistoryDB & L2DB & API packages tests will need to be addapted to the
TestTransaction generation once is done.

common/tx_test.go

@@ -0,0 +1,27 @@
+package common
+
+import (
+	"database/sql"
+	"database/sql/driver"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestTxIDScannerValue(t *testing.T) {
+	txid0 := &TxID{}
+	txid1 := &TxID{}
+	txid0B := [12]byte{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}
+	txid1B := [12]byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
+	copy(txid0[:], txid0B[:])
+	copy(txid1[:], txid1B[:])
+
+	var value driver.Valuer
+	var scan sql.Scanner
+	value = txid0
+	scan = txid1
+	fromDB, err := value.Value()
+	assert.NoError(t, err)
+	assert.NoError(t, scan.Scan(fromDB))
+	assert.Equal(t, value, scan)
+}