Cloud Notification: support enhanced notification

[jimtng]

add title, on_click, attachment, and buttons

See openhab/openhab-addons#16938

[ccutrer]

given the 4 branches here, I'd suggest building up the args list dynamically:

args = []
if email
  args.push(:send_notification, email)
else
  args.push(:send_broadcast_notification)
end
args.push(msg.to_s, icon&.to_s, severity&.to_s)

if Core.version >= Core::V4_2
  buttons ||= []
  buttons = buttons.map { |title, action| "#{title}=#{action}" } if buttons.is_a?(Hash)
  raise ArgumentError, "buttons must contain (0..3) elements." unless (0..3).cover?(buttons.size)

  args.push(on_click&.to_s, attachment&.to_s, buttons[0]&.to_s, buttons[1]&.to_s, buttons[2]&.to_s)
end

NotificationAction.__send__(*args)

[jimtng]

So elegant! Thanks, master!