[kernel][formatting] Formatting pass on core kernel code

Also ran through 'astyle -j -A2' prior to running through clang-fmt,
which adds braces to one line conditionals.

Tested: build and runtests on arm and x86

Change-Id: I888c1ce43dbe12a936a3f13d89c5f8dc16ccab6a

[kernel] Move interval checking utilities to new header

These utilities are more widely applicable and rather error-prone to
implement, so let's share the code.

Change-Id: Ic01dc7c2cc000bfe6709ff16adcf7764e36f7f45

[kernel][arm64] Move the kernel run address out of the Big Kernel Map

-Added code in early boot to remap wherever the kernel was loaded to
approximately -4GB (KERNEL_LOAD_OFFSET still applies)
-Simplfy the mmu_initial_mapping stuff a bit, remove the DYNAMIC flag,
which wasn't used.
-Fix up the boot allocator very early in arm64 to figure out where
physical memory is.

ZX-1238 # Done

Change-Id: Ib43eb9288c79e01253c5c4499278e2fe83602bd1

[kernel][bootalloc] move the boot time allocator into the BKM, instead of relying on pages off the end of the kernel

-In prep for relocating the kernel to different places in kernel space
without having to have the pages immediately after it also mapped.
-This is sort of a step back in safety/security since we're now going to
hold pointers into the BKM, but the longer term goal is to remove the
boot allocator altogether.

Change-Id: I9aa81ae1677a81070ec2f232d63aac91f4ac9e78

[vmm] Remove dead declarations of vmm_init and vmm_preheap

Change-Id: I3b4f108df2662705c3f0e51ebfa431c831242876

[vmm] Remove dead extern declaration from vm_priv.h

Change-Id: Ia135e47ccbf2a8e326645fbe1b51811aae09e4e3

[kernel][vm] move vm.h to the new spot and remove some unused code

Change-Id: I69f1b804fb95dd44e3e0619943e8809519aa82ca

[kernel][vm][formatting] mostly reordering includes after the rename

Change-Id: I8d94a8580ddd0233e036475bd6d4603f5881614f

[zircon][mxtl->fbl] Rename mxtl to fbl

Change-Id: Ie21b6498e1bfb0a7fa0315e40b9e5c3ee78646be

[kernel][vm] move kernel/kernel/vm to just kernel/vm

Change-Id: I8f724a9f8a61415712661d1fdd3dc4e1c70cf620