Add swiftlint

[pepicrft]

Short description 📝

As @marciniwanicki suggested Swiftformat and Swiftlint have different goals and they can be used together within the same project.

Solution 📦

I've added Swiftlint back and fixed a few issues that were reported as warnings.

[ollieatkinson]

🏖

[codecov]

Codecov Report

Merging #245 into master will increase coverage by 0.28%.
The diff coverage is 25.8%.

@@            Coverage Diff             @@
##           master     #245      +/-   ##
==========================================
+ Coverage   84.52%   84.81%   +0.28%     
==========================================
  Files         252      252              
  Lines        8919     8895      -24     
==========================================
+ Hits         7539     7544       +5     
+ Misses       1380     1351      -29

Impacted Files	Coverage Δ
...rces/TuistKit/Generator/GeneratorModelLoader.swift	83.05% <ø> (ø)	⬆️
Sources/TuistKit/Graph/GraphCircularDetector.swift	100% <ø> (ø)	⬆️
Sources/TuistKit/Graph/GraphLoadingError.swift	78.12% <ø> (-0.67%)	⬇️
Sources/TuistKit/Commands/InitCommand.swift	95.15% <ø> (ø)	⬆️
Sources/TuistCore/Utils/Glob.swift	65.17% <ø> (ø)	⬆️
...urces/TuistEnvKit/GitHub/URLSessionScheduler.swift	0% <0%> (ø)	⬆️
Sources/TuistKit/Generator/ProjectGenerator.swift	10.29% <0%> (+3.07%)	⬆️
Sources/TuistKit/Linter/TargetLinter.swift	94.73% <100%> (+0.45%)	⬆️

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