Splitting out UEFI bootloader code from kernel

Now the bootloader should be responsible for all initial setup,
loading the kernel, and then handing off to the kernel with
proper data in place.

src/boot/memory.h

@@ -0,0 +1,13 @@
+#pragma once
+#include <efi.h>
+
+EFI_STATUS memory_virtualize();
+
+EFI_STATUS memory_get_map(
+    EFI_MEMORY_DESCRIPTOR **buffer,
+    UINTN *buffer_size,
+    UINTN *key,
+    UINTN *desc_size,
+    UINT32 *desc_version);
+
+EFI_STATUS memory_dump_map();