[RFC]: WorkerRunner should keep a watch on memory growth

Overview

Now that we have a WorkerRunner capability, we need to ensure that we warn users of "monotonic memory growth" - this would be a sure sign that a memory leak is occurring. A simple "heap size" monitoring per start & end of the target run SHOULD suffice.

Goals & non-goals

Goals

1. at the start and end of a worker run, we should record the heap size
2. if we noticed that the heap size is growing at some slope above X, we should issue a warning to the user (at least at the end)

Non Goals

1. this should not be a feature to amend the --profile feature

Test Plan

• We will leverage an E2E test + a dummy-leaky-worker implementation to help us always identify a memory leak during an execution