Fix: tests: add cli/params/test_params to Makefile and fix it

Fix: tests: add cli/params/test_params to Makefile and fix it

The test bt_plugin_params.py has been broken for a while, because guess
what?  It's not ran by the testsuite!

So first, add it to the Makefile.

Then, update the value types expected by the component class.  I made it
so it raises an exception if it gets an object of a type it doesn't
expect.  That should make the test a bit more robust.

Change-Id: I1749287e7d0e61d8b46d905b2a7ded13ec07283a
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/2254
Tested-by: jenkins <jenkins@lttng.org>
Reviewed-by: Francis Deslauriers <francis.deslauriers@efficios.com>