Support of >2d parameter dims in `MediaConfigList`

[wd60622]

The MediaConfigList should support more than (date, channel) inputs as the AdstockTransformation and SaturationTransformation do.

For instance, the following will likely not work:

# (date, channel, geo)
X = ...

media_transformation = MediaConfigList(...)

coords = {
    "date": ..., 
    "channel": ...,
    "geo": ...,
}
with pm.Model(coords=coords):
    transformation = media_transformation(X)