Addition of autocomplete parameter

[MichalLauer]

Hello @pvictor,

First of all, I'm not sure why the whole files are marked as changed because I only updated function parameters, documentation and selectTag creation. If you happen to know why is that I'm happy to redo the PR.

This PR fixes a common Mozila bug as seen for example here:

• Inputs are not restored to original state after reload in firefox rstudio/shiny#3763
• Widget values persist across page reloads on Firefox ESR rstudio/shiny#2293

An ease reprex is this code:

library(shiny)
library(shinyWidgets)

ui <- fluidPage(
  pickerInput(
    inputId = "somevalue",
    label = "My label",
    choices = c("a", "b", "c"),
    autocomplete = FALSE
  ),
  multiInput(
    inputId = "somevalue2",
    label = "My label",
    choices = c("a", "b", "c"),
  ),
)

server <- function(input, output, session) { }

shinyApp(ui = ui, server = server)

If you run this code in Mozilla, select any picker/multiPicker value and refresh the site, the option is cached and kept on. This can be fixed by adding autocomplete = "off" to the HTML element, which is what this PR does.

I only found this issue with these two widgets, but I'm happy to add it to more widgets if you find it appropriate. I can also move the parameter into the options list() - again, what you think fits this package the best :)

Thanks for your development and if any further changes are needed, feel free to let me know.

Edit: It just occurred to me that I didn't update NEWS.md/Package version... If that's something I should include, please, let me know.

[pvictor]

Thank you !
No worries, I will update NEWS and docs.

Victor