BENCHMARKING: Record timing and memory stats for the various steps in futures

Record timing and memory stats for the various steps in futures, e.g. creation, identification of global variables, exporting globals, launching future, time for future to complete, collection of value/exceptions etc. This should be done (optional?) for all types of futures.

Start by mapping the future lifecycle steps named in the issue: creation, global-variable identification and export, launch, completion, and value or exception collection. Compare how these steps apply across the different future types, then define optional timing and memory statistics and verify that they can be recorded for each type.

Written by the indexing model from the issue text.