feat: side effect system

[icepuma]

I'm submitting a

• bug fix
• feature
• documentation addition

What is the motivation / use case for changing the behavior?

The PR adds the first implementation of our side-effect system.

[codecov-commenter]

Codecov Report

Patch coverage: 67.93% and project coverage change: +0.17 🎉

Comparison is base (60bf7e9) 44.79% compared to head (bafaa66) 44.96%.

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #322      +/-   ##
==========================================
+ Coverage   44.79%   44.96%   +0.17%     
==========================================
  Files          82       82              
  Lines        2902     2942      +40     
==========================================
+ Hits         1300     1323      +23     
- Misses       1602     1619      +17     

Impacted Files	Coverage Δ
app/src/commands/apply.rs	0.00% <0.00%> (ø)
lib/src/actions/group/providers/macos.rs	0.00% <0.00%> (ø)
lib/src/actions/group/providers/mod.rs	25.00% <ø> (ø)
lib/src/actions/user/providers/macos.rs	0.00% <0.00%> (ø)
lib/src/actions/user/providers/mod.rs	25.00% <ø> (ø)
lib/src/atoms/command/exec.rs	45.71% <0.00%> (-1.35%)	⬇️
lib/src/atoms/mod.rs	13.33% <0.00%> (-2.06%)	⬇️
lib/src/atoms/file/chown.rs	62.29% <57.89%> (-2.52%)	⬇️
lib/src/atoms/file/contents.rs	65.62% <63.63%> (-2.24%)	⬇️
lib/src/atoms/file/link.rs	58.53% <66.66%> (+0.20%)	⬆️
... and 8 more

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[martintc]

LGTM