USB OTG support
This is the first beta of supporting USB OTG removable storage devices as a source of repos and mirrors. This is included under the "nearby" section since it provides the UX for prompt the user for the required permissions and the conceptual link to non-network repositories. This also includes auto-detection via USB plug/unplug events. It is quite basic, and while functional, could definitely be presented a lot better to the user. For example, it can take quite a long time to search the USB device for repos, but there is no progress indication.