Extra fancy progress bar on device details view

[lawik]

Top-line sticky bar with gradient box. Pulsing opacity. All the fanciness ;)

This is a reminder for me and @joshk about what we've discussed.

This was the first version of that progress indicator:

defmodule NervesHubWeb.Components.FwupProgressNew do
  use NervesHubWeb, :component

  attr(:fwup_progress, :any)

  def render(assigns) do
    ~H"""
    <div class="sticky top-0 w-full h-0 overflow-visible">
      <div class="h-[1px] bg-success-500" role="progressbar" style={"width: #{@fwup_progress}%"} />
      <div class="text-center pt-2 text-sm animate-pulse">Updating firmware <%= @fwup_progress %>%</div>
    </div>
    """
  end
end