[@nx/expo:run] Allow true as value for --device

[stefan-schweiger]

Currently the --device flag only allows you to specify a specific device name / UUID to launch directly, but expo actually gives you the option to just specify the flag to later select the device from a list.

-d, --device [device]: Device name or ID to build the app on. You can pass --device without arguments to select a device from a list of available options. This supports connected devices as well as virtual devices.

Allow this flag to be used the same when using the nx executor.