Add Env ConfigurationParser

[JSCU-CNI]

This PR adds an environment file parser to the ConfigurationParser helper utility. Fixes #888.

[Miauwkeru]

Thanks for the contribution! We'll discuss these changes with the team and come back to you. Nice to see people using the configuration parser at least :)

[codecov]

Codecov Report

Attention: Patch coverage is 88.70968% with 7 lines in your changes missing coverage. Please review.

Project coverage is 76.68%. Comparing base (e86f92e) to head (6fb4dfe).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
dissect/target/helpers/configutil.py	89.18%	4 Missing ⚠️
dissect/target/plugins/apps/other/env.py	88.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #733      +/-   ##
==========================================
+ Coverage   76.66%   76.68%   +0.02%     
==========================================
  Files         314      315       +1     
  Lines       26955    27017      +62     
==========================================
+ Hits        20664    20719      +55     
- Misses       6291     6298       +7     

Flag	Coverage Δ
unittests	76.68% <88.70%> (+0.02%)	⬆️

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