Add a python bindings sequence test

This example is meant to test whether we can get a sequence's values in
the python binding well or not. It is used in conjunction with the
sequence test in the dir tests/ctf-traces/succeed/sequence.

Signed-off-by: Xiaona Han <xiaonahappy13@163.com>
Acked-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>