GH-36935: [Go] Fix Timestamp to Time dates (#36964)

### Rationale for this change
The previous solution converted everything to nanoseconds first but you end up with overflowing `int64` potentially. Since we've bumped the minimum version of the library to using go1.17+ we can use the newer `UnixMicro` and `UnixMilli` functions to make this easy.

### Are these changes tested?
Yes, unit test is added.

* Closes: #36935

Authored-by: Matt Topol <zotthewizard@gmail.com>
Signed-off-by: Matt Topol <zotthewizard@gmail.com>

go/arrow/datatype_fixedwidth.go

@@ -192,10 +192,16 @@ func TimestampFromString(val string, unit TimeUnit) (Timestamp, error) {
 }
 
 func (t Timestamp) ToTime(unit TimeUnit) time.Time {
-	if unit == Second {
+	switch unit {
+	case Second:
 		return time.Unix(int64(t), 0).UTC()
+	case Millisecond:
+		return time.UnixMilli(int64(t)).UTC()
+	case Microsecond:
+		return time.UnixMicro(int64(t)).UTC()
+	default:
+		return time.Unix(0, int64(t)).UTC()
 	}
-	return time.Unix(0, int64(t)*int64(unit.Multiplier())).UTC()
 }
 
 // TimestampFromTime allows converting time.Time to Timestamp
@@ -327,6 +333,8 @@ const (
 
 var TimeUnitValues = []TimeUnit{Second, Millisecond, Microsecond, Nanosecond}
 
+// Multiplier returns a time.Duration value to multiply by in order to
+// convert the value into nanoseconds
 func (u TimeUnit) Multiplier() time.Duration {
 	return [...]time.Duration{time.Second, time.Millisecond, time.Microsecond, time.Nanosecond}[uint(u)&3]
 }

go/arrow/datatype_fixedwidth_test.go

@@ -159,6 +159,13 @@ func TestTimestampType(t *testing.T) {
 	}
 }
 
+func TestTimestampToTime(t *testing.T) {
+	ts := arrow.Timestamp(11865225600000)
+	tm := ts.ToTime(arrow.Millisecond)
+
+	assert.Equal(t, "2345-12-30 00:00:00", tm.Format("2006-01-02 15:04:05.999"))
+}
+
 func TestTime32Type(t *testing.T) {
 	for _, tc := range []struct {
 		unit arrow.TimeUnit