keep probe_planar_contour when aggregating channels

[RobertoDF]

Fix #3947

[chrishalcrow]

Hello, looking great - good bug catch! There are other annotations we're not forwarding during this function (like probes_info). It'd be amazing if your code generalised to all annotations. I think your basic structure will abstract pretty nicely to all annotations. You'd do something like

for annotation_key in recording.get_annotation_keys():
    check annotation_key is a key in all sub-recordings
    check annotation_value is the same for all sub-recordings
    If it is:
        set the annotation (provided it's not already set: e.g is_filtered gets set somehow)

I think the hard thing is to make the all function work more generally. In my testing, something like

all( np.all(k == first_annotation_value) for k in annotation_values))

seems ok, but maybe someone has a better idea.

[samuelgarcia]

Thanks for this.
I am ok with it.
ANd also ok with @chrishalcrow comments.

[RobertoDF]

@chrishalcrow I think your idea will work well with small modifications from what I proposed. I won´t have time to test this this week though!

[h-mayorquin]

I would like to point out that this is a data point of just passing the whole probe as an attribute and fetch the information from the probe when it is available. Spreading the probe information across annotations and properties makes this type of error harder to trace.