Make switchInput themable

[AshesITR]

library(shiny)
library(shinyWidgets)

shiny::shinyOptions(bootstrapTheme = bslib::bs_theme(primary = "#ff0000"))

shinyApp(
  fluidPage(switchInput("si", "switchInput", offStatus = "primary")),
  function(input, output, session) {}
)

^{Created on 2021-12-06 by the reprex package (v2.0.1)}

Yields this page:

instead of this expected page:

This is the current SCSS for Bootstrap 4, that should be used for theming: https://github.com/Bttstrp/bootstrap-switch/blob/master/src/sass/bootstrap4/bootstrap-switch.scss

[AshesITR]

For whatever reason shinyOptions() doesn't work for me even after the fix, but here is a working piece of code:

library(shiny)
library(shinyWidgets) # On #454 

shinyApp(
  fluidPage(switchInput("si", "switchInput", offStatus = "primary"), theme = bslib::bs_theme(primary = "#ff0000")),
  function(input, output, session) {}
)