GitLab

- Add Group For Selected Nodes
- Add Selected Nodes To Group
- Fit Group To Nodes

There's no reason for the whole CrossAttention object to be repeated when
only the operation in the middle changes.

* improve image preview
- grid mode: align in rectangle instead of first image, show cell border
- individual mode: proper ratio handling

* improve: fix preview button position instead of relative

* improve: image preview - compact mode for same aspect ratio