This commit introduces a way to control core 1.  This is archieved by a
predefined API-Interrupt:  The reset interrupt.  When triggered, it will
bring the core back into its default state and wait for a new vector
address from Epicardium.  Once this vector address is transferred, it
will start the new payload.

This method only works as long as core 1 is responsive to the API
interrupts.  Cases where this might not be the case:

  - During times where core 1 has interrupts disabled
  - When in a higher priority exception handler
  - When core 1 has corrupted its IVT

Signed-off-by: Rahix <rahix@rahix.de>

This allows pycardium to learn which script it should start once it
boots.  Arguments can only be read before any API calls are made.
Afterward they are lost.

To ensure they won't collide with anything during a core 1 restart,
they are offset by 0x20 from the start of the API buffer.

Signed-off-by: Rahix <rahix@rahix.de>

Signed-off-by: Rahix <rahix@rahix.de>