fix: correctly send functional descriptor

The functional descriptor was not sent correctly,
specifically, it was pointed to its address,
instead of the pointer itself. That meant bunch
of irrelevant stuff was sent instead.

feat: use task_result to indicate blocking

There should be no spin loops inside of the
interrupts, so this change removes them,
and instead uses a result system that has
WOULD_BLOCK result. When this result is returned,
it is expected there was no side-effect and the
function can safely be reran later.

feat: implement enumeration fully

docs: add documentation comments to most functions

feat: implement usb devicd cdc descriptors, init, setup