src.ctf.lttng-live: add bt_common_lttng_live_url_parts_deleter

src.ctf.lttng-live: add bt_common_lttng_live_url_parts_deleter

bt_common_lttng_live_url_parts can't be made a C++ object that
automatically manages its memory yet, since it's used in
babeltrace2-cfg-cli-args.c (C code).  Add an RAII type in lttng-live to
automatically call bt_common_destroy_lttng_live_url_parts in two places.

Change-Id: I233a5ba5a2829f4577c4ebbcc1ab0e630d039174
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/8475
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>