test_{field,value}.py: test complex number RHS for binary operations

This patch adds injected tests for numeric field and value test cases in
which the RHS operand of the tested binary operations is a complex
number, both `-23+19j` and `0j`.

This is to ensure that a binary operator applied to a field object or a
value object and a Python complex number returns what's expected by the
langage, so you can do:

    print(my_field + 8+4.2j)

if you wish.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Change-Id: I5cade062e285752d0a917a8b751824b0ebc97f16
Reviewed-on: https://review.lttng.org/c/babeltrace/+/1587
Tested-by: jenkins <jenkins@lttng.org>
Reviewed-by: Francis Deslauriers <francis.deslauriers@efficios.com>