tests: test_ust_constructor: Split test_ust_constructor binary

Observed issue
==============

The single test executable gen-ust-events-constructor covers a lot of
different cases in a single executable. This decreases the legibility of
the test results and debuggability of the test application as many
different pieces are in play.

Solution
========

The test functionality covered by the executable is split into two main
parts: one using a dynamically loaded shared object, and the second
using a statically linked archive.

Known drawbacks
===============

Rather than creating a second test script, the same script is re-used to
run multiple TapGenerator sequentially. This could hamper future efforts
to parallelize python-based tests.

Change-Id: I86d247780ce5412570eada6ebadb83a01547f2b0
Signed-off-by: Kienan Stewart <kstewart@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>