fix(proto): DateTime/DateTime64 with '1970-01-01 00:00:00 UTC'

[YenchangChan]

Summary

I use clickhouse-cli and clickhouse-go to execute the following SQL, but I get different results：

localhost :) select toDateTime('1970-01-01 00:00:00', 'UTC');

SELECT toDateTime('1970-01-01 00:00:00', 'UTC')

Query id: 1b43d122-7f5f-44fa-9f3b-4992bd305998

┌─toDateTime('1970-01-01 00:00:00', 'UTC')─┐
│                      1970-01-01 00:00:00 │
└──────────────────────────────────────────┘

1 row in set. Elapsed: 0.002 sec. 

func main() {
	conn, err := ConnectNative()
	if err != nil {
		panic((err))
	}

	query := "select toDateTime('1970-01-01 00:00:00', 'UTC')"
	var rows driver.Rows
	rows, _ = conn.Query(context.Background(), query)
	for rows.Next() {
		var ts time.Time
		err = rows.Scan(&ts)
		fmt.Println("ts", ts)
	}
}

func ConnectNative() (driver.Conn, error) {
	return clickhouse.Open(&clickhouse.Options{
		Addr: []string{"127.0.0.1:9000"},
	})
}

running result:

ts 0001-01-01 00:00:00 +0000 UTC

I noticed that the reason for the discrepancy in the above results is that ch-go will treat time.Time{} as time.Unix(0,0).UTC(), which is actually not the same in golang:

t1, _ := time.Parse("2006-01-02 15:04:05", "1970-01-01 00:00:00")
t2 := time.Time{}
t3, _ := time.Parse("2006-01-02 15:04:05", "1970-01-01 00:00:01")
fmt.Printf("isZero => t1: %v, t2: %v\n", t1.IsZero(), t2.IsZero())         // isZero => t1: false, t2: true
fmt.Printf("UnixTime => t1: %v, t2: %v, t3:%v\n", t1.Unix(), t2.Unix(), t3.Unix())   // UnixTime => t1: 0, t2: -62135596800, t3:1

The same issue in clickhouse-go: #1222

Checklist

Delete items not relevant to your PR:

• Unit and integration tests covering the common scenarios were added
• A human-readable description of the changes was provided to include in CHANGELOG
• For significant changes, documentation in https://github.com/ClickHouse/clickhouse-docs was updated with further explanations or tutorials