[BUG] panic() does NOT do a full halt

[NotYourFox]

Describe the bug
After revision of MR #23 I noticed that I forgot to disable interrupts in panic() (sys/panic.c). The fix would be to acquire a permanent interrupt lock via cpu_interrupt_lock_acquire().
Feature request: add cpu_full_halt(), which:

1. acquires interrupt reflock
2. disallows force-unlock (set allow_force_unlock flag to false)
3. calls halt()

To Reproduce
Steps to reproduce the behavior:

1. call panic()
2. fire an interrupt
3. that escapes panic state

Expected behavior
panic() does a full halt and is impossible to escape.

[NotYourFox]

In addition:
It would be even better to make a flag, which entirely disallows the release of a reflock, for things like panic(). Though be aware of misuse issues.
Having a concept of access rights to a reflock would be just perfect in theory, though I think that at least requires paging, at most a ton of unnecessary hacks, so it's not the best idea in practice.

[NotYourFox]

Please, don't close issues while related MRs are still open.