fix: dev: include <sys/endian.h> according by checking in meson

The <sys/endian.h> header has existed in macOS since around ~26. This
causes the `htobeNN`/`htoleNN` macros to be redefined in <isc/endian.h>
in terms of <libkern/OSByteOrder.h> when other system headers include
<sys/endian.h>.

Fix this issue by using checking for the existence of <sys/endian.h> in
meson and including it according to the probe result.

Merge branch 'aydin/isc-endian-macos-fix' into 'main'

See merge request isc-projects/bind9!11751