The PIC and APIC code are specific to x86 platforms, so move them out of
the general Interrupts directory to Arch/x86/common/Interrupts directory
instead.
In a previous commit I moved everything into the new subdirectories in
FileSystem/SysFS directory without trying to actually make changes in
the code itself too much. Now it's time to split the code to make it
more readable and understandable, hence this change occurs now.
Function-local `static constexpr` variables can be `constexpr`. This
can reduce memory consumption, binary size, and offer additional
compiler optimizations.
These changes result in a stripped x86_64 kernel binary size reduction
of 592 bytes.
This mostly just moved the problem, as a lot of the callers are not
capable of propagating the errors themselves, but it's a step in the
right direction.
