Fix swap_dim factor order

[mayer79]

Using horizontal dodged barplots requires factor levels to be reverted for both y and fill aesthetic.

When swap_dim = TRUE, the fill aesthetic does not need to be reverted. This PR fixes this.

[codecov-commenter]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (366bd46) 96.39% compared to head (ea6205d) 96.40%.

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Additional details and impacted files

@@           Coverage Diff           @@
##             main      #76   +/-   ##
=======================================
  Coverage   96.39%   96.40%           
=======================================
  Files          18       18           
  Lines         916      917    +1     
=======================================
+ Hits          883      884    +1     
  Misses         33       33           

Files	Coverage Δ
R/utils_plot.R	93.54% <100.00%> (+0.21%)	⬆️
R/utils_statistics.R	97.24% <100.00%> (ø)

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