cpp-common/bt2c: add `Regex`

cpp-common/bt2c: add `Regex`

Add `Regex`, a class wrapping some features of `GRegex` (from glib).

The constructor aborts if the regex pattern fails to compile.  There is
a single `match()` method that returns whether or not the given string
matches the regex.

Change-Id: Ia4cb1542efa91fcf3849d82d047c871d9bf2dbd2
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/12837
Tested-by: jenkins <jenkins@lttng.org>
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>