fix(generic): add alternate binary name for spicetify

[msfjarvis]

Standards checklist:

• The PR title is descriptive.
• I have read CONTRIBUTING.md
• The code compiles (cargo build)
• The code passes rustfmt (cargo fmt)
• The code passes clippy (cargo clippy)
• The code passes tests (cargo test)
• Optional: I have tested the code myself
  • I also tested that Topgrade skips the step where needed

NixOS packages spicetify as spicetify-cli which means the step is skipped on NixOS machines even if spicetify is actually present.

[SteveLauC]

If this binary name is ONLY used on NixOS, it would be great to document it in the comment:)

[msfjarvis]

If this binary name is ONLY used on NixOS, it would be great to document it in the comment:)

Added a comment.

[codecov]

Codecov Report

Merging #486 (f77e2c6) into master (9cd155f) will decrease coverage by 0.15%.
The diff coverage is 2.12%.

@@            Coverage Diff            @@
##           master    #486      +/-   ##
=========================================
- Coverage    3.50%   3.36%   -0.15%     
=========================================
  Files          27      31       +4     
  Lines        3141    4194    +1053     
=========================================
+ Hits          110     141      +31     
- Misses       3031    4053    +1022     

Impacted Files	Coverage Δ
src/command.rs	0.00% <0.00%> (ø)
src/ctrlc/interrupted.rs	0.00% <ø> (ø)
src/error.rs	0.00% <0.00%> (ø)
src/execution_context.rs	0.00% <0.00%> (ø)
src/executor.rs	0.00% <0.00%> (ø)
src/main.rs	0.36% <0.00%> (-0.06%)	⬇️
src/report.rs	0.00% <0.00%> (ø)
src/runner.rs	0.00% <0.00%> (ø)
src/steps/containers.rs	0.00% <0.00%> (ø)
src/steps/emacs.rs	0.00% <0.00%> (ø)
... and 20 more