Show the app overlay panel contents all the time #619
Description
We should show the roku app overlay panel contents all the time, not just when the device is connected. I'd expect the following types of behavior:
- devs can add/edit/remove entries at any point, even if a debug session isn't running. if a debug session isn't running, we just skip the rta/rdb interactions.
- show a status in the panel noting whether we're connected to a device or not (that'll help devs know if their changes will be applied right now or later)
- make sure that any add/edit/delete interactions with images are instant, and don't need to wait for rta/rdb before updating the UI. this might already be the case, but I think i've seen a few situations where if RDB isn't responding, the image won't get added to the panel.
