[efi] Allow for interception of boot services calls by loaded image

When building with DEBUG=efi_wrap, print details of calls made by the
loaded image to selected boot services functions.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
[efi] Print well-known GUIDs by name in debug messages

Signed-off-by: Michael Brown <mcb30@ipxe.org>