Clamp progress bar fill when current is outside 0..total

[taekop]

Setting a progress bar to a value below zero or above total fails when the bar is drawn, and the error then also surfaces from a deferred on.exit():

options(cli.progress_show_after = 0)
f <- function(x) {
  cli::cli_progress_bar("Test", total = 10)
  cli::cli_progress_update(set = x)
  cli::cli_progress_done()
}
f(-1)
#> Error in `rep()`: invalid 'times' argument
f(11)
#> same error

make_progress_bar() passes width * percent and width - complete_len to rep(), which is negative for percent < 0 or percent > 1. The fill is now clamped to the range 0..1. Values inside that range render exactly as before, and pb_percent still shows the real value (e.g. 110%).

Closes #580

[gaborcsardi]

Thanks!