lsof: add update-alternatives logic

Some distributions (NI LinuxRT) provide both busybox-lsof and
full-featured lsof implementations. When users install the full-featured
lsof package, the full-binary fails to replace the bbox-binary in PATH,
because `lsof` contains no update-alternatives logic.

Inherit the update-alternatives bbclass and assert that the
full-featured lsof package has higher priority than the busybox
implementation.

Co-Authored-By: Kyle Roeschley <kyle.roeschley@ni.com>
Signed-off-by: Alex Stewart <alex.stewart@ni.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>