Draft: wifi: Move hotspot information into a subpage
This introduces lot of changes by moving things around. Fundamentally this modernizes the CcWifiPanel page to use the modern AdwNavigationView.
CcWifiHotspotPage is introduced to contain the Hotspot's QR Code image and the rows with ssd, security, and password. Before the QrCode and info rows were displayed within the main panel view.
To make it work for multiple wifi devices, this makes NetDeviceWifi now emit two signals: "hotspot-row-activated" and "hotspot-turned-off". This makes it easy for the main panel logic to know when to show the hotspot page for any given device.
Fixes #2567