[roll] Roll fuchsia Reland "[kernel][scheduler] Use mp_reschedule_self when holding a spinlock"

This is a reland of commit d87d35461fc1ca3cd2c246be25fecf0e93c2d109

Original change's description:
> [kernel][scheduler] Use mp_reschedule_self when holding a spinlock
>
> This fixes a bug where triggering a reschedule of the calling CPU
> while holding a spinlock could result in an arbitrarily delayed
> preemption.
>
> Now, when holding one or more spinlocks, we use mp_reschedule_self in
> Reschedule and RescheduleMask to trigger a future preemption of the
> calling CPU once it has released its spinlocks and re-enabled
> interrupts.
>
> This change effectively makes holding a spinlock imply that preemption
> is disabled (deferred) and ensure that a deferred preemption will
> occur promptly upon dropping the spinlock and re-enabling interrupts.
>
> While it is now longer necessary to explicitly disable
> preemption (e.g. using AutoPreemptDisabler) around spinlock critical
> sections that are likely to reschedule, it is still a good idea to do
> so because it will likely perform better than this new approach (self
> IPI).
>
> Add kcounter to track number of self-IPI events.
>
> Original-Bug: 42143537
> Original-Bug: 457759524
> Change-Id: I758cd28bff6cb3bdcc368bcef7d66e8ba7184c70
> Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1415574
> Reviewed-by: John Grossman <johngro@google.com>
> Reviewed-by: Corey Tabaka <eieio@google.com>
> Fuchsia-Auto-Submit: Nick Maniscalco <maniscalco@google.com>
> Commit-Queue: Nick Maniscalco <maniscalco@google.com>

Original-Bug: 42143537
Original-Bug: 457759524
Run-All-Tests: true
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1422596
Original-Revision: 3945356324cf44e671f6defb63f7a20f3fdaeb0a
GitOrigin-RevId: 9548f5f34ea35a8752d6e12b196a83ffc24122a4
Change-Id: I3f0d424d8efc4cc5403596bf7bb8d27875c7d39c