cpp-common: add FileUP

cpp-common: add FileUP

Add a unique_ptr type to manage the lifetime of a `FILE *`, with a
custom deleter that calls fclose.

Change-Id: Idded4546d2a709cd0652975ef83c3ad6a0f511bc
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/8172
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/10843
Tested-by: jenkins <jenkins@lttng.org>
CI-Build: Philippe Proulx <eeppeliteloop@gmail.com>