Panic on control buffer overflow

[haata]

• When writing larger interface descriptors it's possible to overflow the buffer (even on LS/FS USB 2.0)
• Cleanup get_descriptor and accept_writer to forward the error
• Then unwrap() it inside get_descriptor
  • unwrap() will panic regardless of the logging mechanism and give a useful error message (e.g. defmt): ERROR panicked at 'called Result::unwrap() on an Err value: BufferOverflow'
  • We want to panic as continuing usually halts/suspends the USB device which will usually retry enumeration a few times until the host gives up
  • This is most common during initial enumeration, but it's also possible when requesting debug descriptors (e.g. lsusb)
• Ideally we should return some sort of error that recommends enabling the control-buffer-256 feature but this isn't straightforward with the current design