Cannot build with XDP support against libbpf > 1.0

[cconverse711]

Bug description

Describe the bug
Building with XDP support enabled fails against libbpf > 1.0, since xsk.h was moved from libbpf to libxdp. Originally raised in #1635

Code example to reproduce

$ cat /usr/include/bpf/libbpf_version.h | grep "LIBBPF_.*_VERSION"
#define LIBBPF_MAJOR_VERSION 1
#define LIBBPF_MINOR_VERSION 3

$ cat /etc/os-release | grep PRETTY_NAME
PRETTY_NAME="Ubuntu 24.04.4 LTS"

$ cmake .. -DPCAPPP_USE_XDP=ON
$ make
/home/user/code/PcapPlusPlus/Pcap++/src/XdpDevice.cpp:8:10: fatal error: bpf/xsk.h: No such file or directory

Expected behavior
Code should compile successfully, with XDP support

PcapPlusPlus versions tested on

PcapPlusPlus master branch

Other PcapPlusPlus version (if applicable)

No response

Operating systems tested on

Linux

Other operation systems (if applicable)

No response

Compiler version

g++ 13.3.0

Packet capture backend (if applicable)

XDP