`ctf` plugin: add `ctf::IntRange` class template

`ctf` plugin: add `ctf::IntRange` class template

This new class template is conceptually the same as the libbabeltrace2
equivalent (`bt2::ConstIntegerRange`), but it's templated and avoids
having to make libbabeltrace2 function calls to access data.

That being said, the contains() and intersects() methods don't have
their libbabeltrace2 equivalent.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Change-Id: Ic2ab4b4b8dd97bce8dc69a1a7331fed8a46d9254
Reviewed-on: https://review.lttng.org/c/babeltrace/+/7922
Reviewed-on: https://review.lttng.org/c/babeltrace/+/12251