All kernel APIs should return a result_t<> type

[egranata]

This is a rather large change, and needs some design, but the basic idea is that there would be a templated type kernel_result_t<T> that basically acts as a "success, here's your T thingy back" or "error, here's a status code"

This type should, additionally, induce a kernel panic if the caller of the API does not - at least - check for success, even if the actual return value is unused.