move libraries/USBHost to hardware/arduino/sam/libraries/USBHost and for samd

cores/arduino/Arduino.h

cores/arduino/USB/USB_host.h

cores/arduino/USB/samd21_host.c

cores/arduino/USB/samd21_host.h

cores/validation/validation_usb_host/build_as6/test.cppproj

...ries/USBHost/examples/ADKTerminalTest/ADKTerminalTest.ino

...SBHost/examples/KeyboardController/KeyboardController.ino

...ries/USBHost/examples/MouseController/MouseController.ino

libraries/USBHost/examples/USB_desc/USB_desc.ino

libraries/USBHost/examples/USB_desc/pgmstrings.h

libraries/USBHost/keywords.txt

libraries/USBHost/library.properties

libraries/USBHost/src/KeyboardController.cpp

libraries/USBHost/src/KeyboardController.h

libraries/USBHost/src/MouseController.cpp

libraries/USBHost/src/MouseController.h

libraries/USBHost/src/Usb.cpp

libraries/USBHost/src/Usb.h

libraries/USBHost/src/UsbCore.h

libraries/USBHost/src/address.h