[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.cpp

@@ -106,7 +106,7 @@ pci_device::pci_device(pci_group &group, uint8_t bus, uint8_t device, uint8_t fu
         // Walk the extended capabilities list
         uint8_t next = m_base[13] & 0xff;
         while (next) {
-            pci_cap *cap = reinterpret_cast<pci_cap *>(kutil::offset_pointer(m_base, next));
+            pci_cap *cap = reinterpret_cast<pci_cap *>(offset_pointer(m_base, next));
             next = cap->next;
             log::debug(logs::device, "  - found PCI cap type %02x", cap->id);