ctf: make src.ctf.fs group inputs by UUID in `babeltrace.support-info` query

ctf: make src.ctf.fs group inputs by UUID in `babeltrace.support-info` query

When replying to the `babeltrace.support-info` query, the src.ctf.fs component
class currently groups all recognized CTF inputs in a single `ctf`
group.  It then internally groups traces with the same UUID together to
process them as a single trace (to support LTTng's session rotation
feature).

This commit makes it group the inputs by UUID, which will naturally
assign all inputs beloning to one logical trace to one instance of
src.ctf.fs.  Input traces without UUID are not placed in a group,
meaning that they will have their own src.ctf.fs component.

This paves the way to simplifying src.ctf.fs to support only a single
(logical) trace.

I added a test CTF trace for this, `session-rotation`, which consists of
two traces with three rotation chunks each.  We therefore expect to have
two groups with three inputs each.

The new Python test checks the `babeltrace.support-info` query directly.
I also added a new .expect file for this new test trace, it will at
least verify that we have the right number of streams (which will be off
if the grouping doesn't work as intended).

Change-Id: I13374fff9bafa94c5d8f4b6bac1c64afadef7a46
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/1844
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>
Reviewed-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Tested-by: jenkins <jenkins@lttng.org>