Collect memory information alongside stack

Currently, we collect just what the current function stack is at each tick. In order to aid memory debugging, we should also collect memory usage at each tick.

This would help immensely with understanding when memory is actually used, as it's rarely the case that this is actually at the memory error location.

See also:
* https://phabricator.wikimedia.org/T399210
* https://github.com/arnaud-lb/php-memory-profiler

No file or test is named. Start by tracing the existing code that collects the current function stack at each tick, then review the linked PHP memory profiler for relevant memory measurements. Done means memory usage is collected alongside the stack for every tick.

Written by the indexing model from the issue text.