[C++] Change Acero Aggregate output order

[asfimport]

At the moment Acero Aggregates output contains aggregate fields followed by key fields. In Substrait this is the other way around. Also, it is not necessary to keep this static and use a project node to fulfill the requirement. It is rather important to modify this order and update the corresponding test cases. 

Reporter: Vibhatha Lakmal Abeykoon / @vibhatha

_{Note: This issue was originally created as ARROW-17656. Please see the migration documentation for further details.}

[asfimport]

Apache Arrow JIRA Bot:
This issue was last updated over 90 days ago, which may be an indication it is no longer being actively worked. To better reflect the current state, the issue is being unassigned per project policy. Please feel free to re-take assignment of the issue if it is being actively worked, or if you plan to start that work soon.

[westonpace]

Closing as a duplicate of #33616