Provide full list of outputs on aggregation

Currently, due to some of the use-cases that we have for this, if the client inputs `[x1, x2, ..., xn]` as their measurement, then the aggregation function will only return the value `xi` that satisfies the threshold requirement, rather than `[x1, ..., xi]`. I think the latter case is more accurate, and doesn't require running the aggregate function individually for each layer of measurements.

Start by locating the aggregation function responsible for threshold-based measurement outputs and inspect how it handles an input such as [x1, x2, ..., xn]. The work is done when the aggregation returns the prefix [x1, ..., xi] rather than only xi for the matching threshold, with tests covering this behavior.

Written by the indexing model from the issue text.