CLI-1171: Home directory errors on Windows

[Jura]

Motivation

Fixes #1610

Proposed changes

extending env variable testing condition to avoid PHP error when the var is not present

Alternatives considered

Testing steps

1. Follow the contribution guide to set up your development environment or download a pre-built acli.phar for this PR.
2. Clear the kernel cache to pick up new and changed commands: ./bin/acli ckc
3. (add specific steps for this pr)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (5fdac94) 91.68% compared to head (1bd01cb) 91.78%.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1611      +/-   ##
============================================
+ Coverage     91.68%   91.78%   +0.09%     
  Complexity     1809     1809              
============================================
  Files           124      124              
  Lines          6485     6485              
============================================
+ Hits           5946     5952       +6     
+ Misses          539      533       -6     

Files	Coverage Δ
src/Helpers/LocalMachineHelper.php	62.22% <100.00%> (+4.44%)	⬆️

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[danepowell]

Thanks for the PR! I added some test cases but I cannot push to your fork, and I want to make sure you get credit for this PR. Can you please cherry-pick this commit into your fork? c359286

[Jura]

Thanks @danepowell, I couldn't cherry pick from the fork you referenced (insufficient permissions) so transferred changes manually. If you want to keep your name on the commit - we can reverse it and you could commit to my fork, I added yo as a contributor to https://github.com/undp/acquia-cli

[danepowell]

I'm not picky. Looks good, thanks!