Currently dashboard with Multi-window set up does not really run the
result array vrl functions. This pr adds support for vrl function when
`/_search_multi_stream` is used. When `per_query_response` is true, and
the vrl function is result array vrl function, the function is applied
on the whole combined response (including both the time windows). The
input of the result array vrl function becomes a 2d array where each
child array represent a time window.
Otherwise, if `per_query_response` is false, or the vrl function is not
result array vrl function, then the function is applied individually on
every result of every time-window queries.
Subhra264
3760b55cf9