Run styler::style_pkg() to make code formatting more consistent

[chartgerink]

This PR runs styler::style_pkg() to style the codebase (according to the tidyverse specs). I am introducing this PR because:

• The package code style deviates from the general Epiverse-TRACE style
• This deviation is not documented and creates ambiguity as to what style is applied
• Because the style is not defined, it is unclear how to contribute in style code
• It is also unclear whether the style is applied consistently throughout the current codebase

By running styler::style_pkg() I am attempting to create a baseline and ensure that future contributions can be confident. In case this is not desirable, I would like to request explicit documentation as to what code style is applied (e.g., in the package vignette). I realize we do not have hard standards on this in the blueprints at this time, and I do think there is value in a consistent and clear code style for the code, the maintainer, and for the contributors.