Weighted aggregations `torch_geometric.nn.aggr.Aggregation`

🚀 The feature, motivation and pitch

The current API of torch_geometric.nn.aggr.Aggregation seems to be unnecessarily limited with respect to edge weights. At least some architectures introduce edge weights, with GCN being the most prominent one. For mean aggregation, it is simple to work around this with a custom message passing / convolution that multiplies features with edge weights. However, for most other weighted aggregations (e.g. median, quantiles, standard deviation, ...) it is not.

Alternatives

Add edge weights to aggregations API

Additional context

No response