Migrate UsbManager to reference AIDL USBGadget interface

UsbManager referenced the HIDL Gadget HAL interfaces for populating and
documenting its fields. As the HIDL interfaces are now deprecated, this
CL changes UsbManager to reference AIDL Gadget HAL interfaces instead.

The fields cannot be initialized as `GadgetFunction.XYZ` because of
b/243718774. So a javadoc reference has been added instead.

Also does some formatting fixes for the lint gods.

Test: Manually tested that USB gadgets are configured properly after
      the change
Bug: 218791946
Change-Id: I524bb44768f3ec947487bfe266bc79713e544004