Allow logs from memray core

I am currently unable to see any of the core memray logs when running pytest-memray with my project's test suite.

As an example, I am trying to see if support for greenlet is running inside memray when running pytest-memray, but I cannot get memray core to print or log any lines whether greenlet support is enabled or not. I have tried building memray from scratch and adding log lines and prints to both when greenlet is detected and not detected, but nothing shows up not matter how I run pytest-memray or what logging level I use. I can see the greenlet log when running pytest directly on memray without pytest-memray e.g. `memray run -m pytest ...` in the same environment.

Perhaps this is already implemented somewhere, but I cannot find it on the docs or see an option to enable anything like this.

Ideally there would be an option to get output from core memray code, so we can debug issues directly when using pytest-memray without having to run pytest in memray.

Start by comparing `memray run -m pytest ...` with the same suite through pytest-memray, focusing on why core memray logs are visible in one invocation but not the other. Read the pytest-memray integration and any logging configuration it uses. Done means an option allows core memray output while running pytest-memray, including visibility of the greenlet support log.

Written by the indexing model from the issue text.