Port Ceno Settings options from the extension to application settings

This MR is related to #13 (closed), in which it is suggested that we make many of the Ceno settings accessible from the main application Settings page (also known as the "General Settings"). In addition to making most of the options available via the main settings, this MR also removes the "Ceno Settings" option from the toolbar menu. Now, the extension settings page can be reached via the "Ceno Network Details" option in the main settings. Further consideration is needed for adding the network details and the BT bootstrap options to the main settings page (or as a sub-page), but this MR takes care of the most important settings and, in my testing, appears stable enough to release to the beta channel.