Replace DeviceConnectionInterface with io.ReadWriteCloser for DTX

[dmissmann]

The DeviceConnectionInterface doesn't look like a very useful interface. Most of the service should only require a io.ReadWriteCloser to communicate with the device. And that's what kind of already happens, but since DeviceConnectionInterface exposes the io.Reader and io.Writer interfaces on separate methods, we still have to go through that instead of simply using the io.ReadWriteCloser interface directly.

For DTX the changes are very minimal, and most other services should not be more complex as most of the additional methods in DeviceConnectionInterface are either used by the debugproxy or lockdown.

[danielpaulus]

The DeviceConnectionInterface doesn't look like a very useful interface. Most of the service should only require a io.ReadWriteCloser to communicate with the device. And that's what kind of already happens, but since DeviceConnectionInterface exposes the io.Reader and io.Writer interfaces on separate methods, we still have to go through that instead of simply using the io.ReadWriteCloser interface directly.

For DTX the changes are very minimal, and most other services should not be more complex as most of the additional methods in DeviceConnectionInterface are either used by the debugproxy or lockdown.

"Doesn't look very useful".. you are really hurting my feelings here @dmissmann 😭
🤣 I think the change makes sense.

If you can fix the test, we can merge this.