phase 2, removal of extraneous signaling in favor of llnotificationchannels
made notificationchannels work better with overrides and lifetime managed
by creator
- As the class LLToastNotifyPanel is deprecated, made the class LLToastScriptTextbox derived directly from LLToastPanel.
- Added callback for ignore button.
Now LLToastScriptTextbox has its own XML, therefore it's not needed to dynamically create toast panel.
Since LLToastNotifyPanel is deprecated all new notification toasts should be created this way.