Adds Persistent fils logs to testing

[Choudhry18]

Summary

Adds persistent file logs to snapshot testing that can be viewed later. This builds on to #11762 and attempts to resolve #8351 . This introduces a dedicated log directory that keeps logs from test runs, unless another directory is specified.

Test Plan

I have manually checked if there is a log file for each test file after running the tests. I do believe testing should be a bit more robust, however i am unsure how can that be done - check file logs against cli logs is not easily possible because of print statements in cli.

Discuss

I wanted to get more input on whether there should be log file per command invocation or other other frequency. Currently there is a log file for each test file. To implement one log for each test is quite simple but it requires tediously adding a --log flag to each test.