Replace :lists.foreach with recursive function

[rkallos]

This is a pretty small change in the hot path. It replaces the use of a :lists.foreach call with a recursive function. It also splits out fetch_measurement/3 into separate function heads, though there's no noticeable change in performance there.

The improvements, as measured by tprof, using a simple microbenchmark

• :call_time - The fastest experimental run is 3% faster than the fastest control run on my personal computer (~86ms faster)
• :call_memory - 10% reduction in words allocated (6 words per call to :telemetry.execute) in experimental runs. I suspect this allocated memory is related to the closure that is passed to :lists.foreach.

[hauleth]

I have similar changes as well, but with more extras. However currently these depends on #64 in my repo. I probably could clean this up to make it independent, but it is almost exactly the same as yours.

[rkallos]

That sounds great! I merged your other PR, so feel free to open a new one.

[rkallos]

Closing. #69 covered this work and took it further.