Add a printer factory to simplify construction of printer drivers (#11)

Co-authored-by: Moritz Martinius <mm@cloudprinters.de>
Reviewed-on: moritz/ptouch-prnt#11

src/libusbwrap/UsbDevice.hpp

@@ -47,8 +47,7 @@ class UsbDevice : public IUsbDevice {
                       unsigned int timeout) override;
 
     // getters
-    const uint16_t getVid() override;
-    const uint16_t getPid() override;
+    const usbId getUsbId() override;
     const device::Speed getSpeed() override;
     const uint8_t getBusNumber() override;
     const uint8_t getPortNumber() override;