Make matrixInputs' labels' classes like other Shiny inputs'

[JohnADawson]

Themes affect matrixInputs' labels differently from other Shiny inputs'. For example, in the following application the space between the matrixInput and its label is too little.

ui <- shiny::fluidPage(
  theme = bslib::bs_theme(),
  shiny::fluidRow(
    shiny::column(3L, shinyMatrix::matrixInput("matrix", "Label")),
    shiny::column(3L, shiny::textInput("text", "Label")),
    shiny::column(3L, shiny::numericInput("numeric", "Label", 0L)),
    shiny::column(3L, shiny::radioButtons("radio", "Label", letters[seq_len(3L)]))
  )
)

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

shiny::shinyApp(ui, server)

The cause is that matrixInputs' labels do not have the class "control-label". This pull request makes matrixInputs' labels' classes like other Shiny inputs'. The example above becomes

[aneudecker]

Thanks for the PR! Looks good to me.
Could you increase the version in the DESCRIPTION file to 0.8.1, then we can merge the PR

[aneudecker]

Merged. Thanks for your contribution!