Improve performance by skipping AccessLogHandler if it writes to /dev/null

[clue]

This changeset improves performance noticeable by skipping the AccessLogHandler if it writes to /dev/null. This is commonly used when the access log is not needed, such as when running behind a reverse proxy or when benchmarking the raw application performance.

This can be easily reproduced by running a benchmark against any of the examples like this:

$ php public/index.php >/dev/null
$ docker run -it --rm --net=host jordi/ab -n100000 -c100 -k http://localhost:8080/

# old: 22678 requests per second
# new: 29232 requests per second

(Also posted in https://twitter.com/another_clue/status/1764649661749690540)

This builds on top of the recent access log path additions from #247. In particular, this optimization works both when explicitly configured to log to /dev/null or when implicitly logging to console output that is piped to /dev/null.

This is a pure performance optimization that comes with 100% code coverage and does not otherwise affect the public API, so it should be safe to apply. This currently focuses on Unix-based platforms (Linux / Mac) as the main deployment target, but similar optimizations should be possible on Windows (using nul instead of /dev/null).

You're looking at several days worth of work, especially for testing this across multiple platforms. If you enjoy this change and want to help us continue to ship more improvements, consider supporting this project, for example by becoming a sponsor ❤️

Builds on top of #247
Refs #169

[SimonFrings]

Nit: Just noticed two typos in test names

[SimonFrings]

Nice, pull request looks good to me 👍