[kernel] Move more from kutil to kernel

The moving of kernel-only code out of kutil continues. (See 042f061)
This commit moves the following:

- The heap allocator code
- memory.cpp/h which means:
  - letting string.h be the right header for memset and memcpy, still
    including an implementation of it for the kernel though, since
    we're not linking libc to the kernel
  - Changing calls to kalloc/kfree to new/delete in kutil containers
    that aren't going to be merged into the kernel
- Fixing a problem with stdalign.h from libc, which was causing issues
  for type_traits.

src/kernel/pci.h

@@ -3,7 +3,7 @@
 /// PCI devices and groups
 
 #include <stdint.h>
-#include "kutil/memory.h"
+#include "memory.h"
 
 struct pci_group;
 enum class isr : uint8_t;
@@ -126,7 +126,7 @@ struct pci_group
     /// \returns    A pointer to the memory-mapped configuration registers
     inline uint32_t * base_for(uint8_t bus, uint8_t device, uint8_t func)
     {
-        return kutil::offset_pointer(base,
+        return offset_pointer(base,
                 pci_device::bus_addr(bus, device, func) << 12);
     }