Pre-aggregations with elasticsearch as datasource are not timezone aware

When creating pre-aggregations with different time zones and elasticsearch as a data source, the time dimension of the results is not converted to each applicable time zone because 'convertTz' is not implemented in the "ElasticSearchQuery" adapter. The convertTz function code can be as follows:

```javascript
public convertTz(field: string): string {
const tz = moment().tz(this.timezone);
// TODO respect day light saving
const [hour, minute] = tz.format('Z').split(':');
const [hourInt, minuteInt] = [parseInt(hour, 10), parseInt(minute, 10) * Math.sign(parseInt(hour, 10))];
let result = field;
if (hourInt !== 0) {
result = `TIMESTAMPADD('hour', ${hourInt}, ${result})`;
}
if (minuteInt !== 0) {
result = `TIMESTAMPADD('minute', ${minuteInt}, ${result})`;
}
return result;
}
```