Add multi-period support to Xero Profit and Loss reports#1916

The Xero connector currently returns only one Profit and Loss reporting period per query, even when a broader Windsor date range such as this_year is selected.

Xero’s Reports/ProfitAndLoss API supports comparative reporting through the periods and timeframe parameters. For example, a report for August 2026 compared with the previous seven months should use the equivalent of:

fromDate=2026-08-01
toDate=2026-08-31
periods=7
timeframe=MONTH

At present, users can retrieve each month by creating separate monthly queries and combining them downstream, but Windsor does not return all comparison periods in a single response