refactor: sort RUNENV debugging log output

[jameslamb]

Running with logging.level = "DEBUG", scikit-build-core emits a log message listing environment variables for the build, like this:

2023-06-05 00:48:26,822 - scikit_build_core - DEBUG - RUNENV:
  SYSTEM_PULLREQUEST_SOURCECOMMITID=77b0ed1470cbf63d39ddae10915e96cea2804783
  BUILD_QUEUEDBY=Microsoft.VisualStudio.Services.TFS
  CONDA_SHLVL=1
  LC_ALL=en_US.UTF-8
  LD_LIBRARY_PATH=/usr/local/lib64:/opt/rh/gcc-toolset-12/root/usr/lib64:/opt/rh/gcc-toolset-12/root/usr/lib:/opt/rh/gcc-toolset-12/root/usr/lib64/dyninst:/opt/rh/  gcc-toolset-12/root/usr/lib/dyninst:/usr/local/lib
  CONDA_EXE=/opt/miniforge/bin/conda
  AGENT_HOMEDIRECTORY=/__a
  SYSTEM_POSTLINESSPEED=10000
  AGENT_USEWORKSPACEID=true
  SYSTEM_STAGEDISPLAYNAME=__default
  AGENT_VERSION=3.220.2
  SYSTEM_JOBATTEMPT=1
  SYSTEM_TEAMFOUNDATIONSERVERURI=https://dev.azure.com/lightgbm-ci/
  AGENT_TOOLSDIRECTORY=/__t
  INPUT_ARGUMENTS=
  SYSTEM_DEFINITIONID=1
  AGENT_DISABLELOGPLUGIN_TESTFILEPUBLISHERPLUGIN=true
  LANG=en_US.UTF-8
  ...

I've found that very useful when trying to debug build issues in a project I'm working on (microsoft/LightGBM#5061).

This PR proposes a change that I think might make it even more useful...sorting that output alphabetically, like this:

2023-06-05 00:48:26,822 - scikit_build_core - DEBUG - RUNENV:
  AGENT_DISABLELOGPLUGIN_TESTFILEPUBLISHERPLUGIN=true
  AGENT_HOMEDIRECTORY=/__a
  AGENT_TOOLSDIRECTORY=/__t
  AGENT_USEWORKSPACEID=true
  AGENT_VERSION=3.220.2
  BUILD_QUEUEDBY=Microsoft.VisualStudio.Services.TFS
  CONDA_EXE=/opt/miniforge/bin/conda
  CONDA_SHLVL=1
  INPUT_ARGUMENTS=
  LANG=en_US.UTF-8
  LC_ALL=en_US.UTF-8
  LD_LIBRARY_PATH=/usr/local/lib64:/opt/rh/gcc-toolset-12/root/usr/lib64:/opt/rh/gcc-toolset-12/root/usr/lib:/opt/rh/gcc-toolset-12/root/usr/lib64/dyninst:/opt/rh/gcc-toolset-12/root/usr/lib/dyninst:/usr/local/lib
  SYSTEM_DEFINITIONID=1
  SYSTEM_JOBATTEMPT=1
  SYSTEM_POSTLINESSPEED=10000
  SYSTEM_PULLREQUEST_SOURCECOMMITID=77b0ed1470cbf63d39ddae10915e96cea2804783
  SYSTEM_STAGEDISPLAYNAME=__default
  SYSTEM_TEAMFOUNDATIONSERVERURI=https://dev.azure.com/lightgbm-ci/

In addition to making the output a bit easier to scan visually (in my opinion), that also makes the use of text-diffing tools to compare log output a bit easier.

Thanks very much for your time and consideration.

[henryiii]

Thanks!