chore: close #210 use styler::style_pkg()

[swsoyee]

Also considering use pre-commit.hooks and {lintr} to set some limitation to code style and auto formatting in later PR, at the same time do not put too much of burdens on other contributors.

Not going to use {lintr} recently, since it will affect too many code.

> styler::style_pkg()
Styling  33  files:
 R/actions.R       ℹ 
 R/add_.R          ℹ 
 R/add.R           ℹ 
 R/append.R        ℹ 
 R/boxes.R         ℹ 
 R/button.R        ℹ 
 R/calendar.R      ℹ 
 R/callbacks.R     ℹ 
 R/color.R         ℹ 
 R/echarts4r.R     ℹ 
 R/facets.R        ℹ 
 R/general.R       ℹ 
 R/geo.R           ℹ 
 R/globe.R         ℹ 
 R/graphic.R       ℹ 
 R/grid.R          ℹ 
 R/grid3d.R        ℹ 
 R/group2series.R  ℹ 
 R/helpers.R       ℹ 
 R/leaflet.R       ℹ 
 R/loading.R       ℹ 
 R/map.R           ℹ 
 R/mark.R          ℹ 
 R/nesting.R       ℹ 
 R/opts.R          ℹ 
 R/plugins.R       ℹ 
 R/proxies.R       ℹ 
 R/themes.R        ℹ 
 R/timeline.R      ℹ 
 R/utils-exports.R ✓ 
 R/utils-pipe.R    ✓ 
 R/utils.R         ℹ 
 R/zzz.R           ℹ 
────────────────────
Status	Count	Legend 
✓ 	2	File unchanged.
ℹ 	31	File changed.
x 	0	Styling threw an error.
────────────────────
Please review the changes carefully!

After this commit, it may need also need to update the Rd and pkgdown site because those examples before functions are been styled as well. I can do the update If needed, too. But I think it will be better to confirmed the first commit at first.

devtools::document()
pkgdown::build_site()