[ion/usb] Add a check for E16 when flashing

[M4xi1m3]

Is your feature request related to a problem? Please describe.
Epsilon 16 introduces massive changes to the Numworks, locking down the platform. It is in the users' interest to add a check if what they are trying to flash is Epsilon 16.

Describe the solution you'd like
Detect, in the DFU code, if we are trying to flash Epsilon 16. This could be done by checking which interrupts vectors are used, because E16 uses a lot more than E15. This would allow to check at the very beginning of the flashing process and show a message to the user warning them that they are going to be locked out of their calculator.

Additional context
We don't know what Numworks will do next to lock users out of the hardware they bought. They could sneakily update the calculators of those using the workshop, for example, so I think this is an important thing to do.