lib: make default query implementation return INVALID_OBJECT, remove UNSUPPORTED...

lib: make default query implementation return INVALID_OBJECT, remove UNSUPPORTED status

Queries against component classes that don't implement the query method
currently return a special UNSUPPORTED status.  There is however no need
for a different status than the one a query method returns when it
doesn't know about the object, INVALID_OBJECT.

Make the default implemention of "query" return INVALID_OBJECT, and
remove any trace of UNSUPPORTED, including in the Python bindings.

Change-Id: I43f59ef749f3803a832a1ad14e640d03424b3420
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/1755
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>
Tested-by: jenkins <jenkins@lttng.org>