Add aggregate values for transactions in search and reports

[techieshark]

Currently it's possible to search for objects, for example for those transactions above/below a set amount or within a time range.

It'd be great to be able to query for a sum of the transactions too (e.g. sum all transactions in 2019). Currently this would require fetching/paginating across all, so server side summation would cut bandwidth and time costs for clients.

[lkorth]

@techieshark thanks for opening an issue. At this time we don't have any plans for offering a query based aggregation like this, but we are continuing to expand the capabilities of search as well as adding more reports to the API and will keep it in mind. I've also brought this to the attention of our reporting team.

I'll leave this issue open for others to vote on it and show interest so we can weigh it against other feature requests we receive.