Pre-aggregations with elasticsearch as datasource are not timezone aware

[ernriveron]

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:

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;
}

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[igorlukanin]

Hi @ernriveron 👋

Thanks for the suggestion! Would you be open to create a PR with these changes?