GitLab

* Start writing gallery example

* Remove the child image fix implementation add code

* add docs

* Apply suggestions from code review
Co-authored-by: Vasilis Vryniotis <datumbox@users.noreply.github.com>

* address review update thumbnail
Co-authored-by: Philip Meier <github.pmeier@posteo.de>
Co-authored-by: Vasilis Vryniotis <datumbox@users.noreply.github.com>

* Change transforms gallery thumbnail

* Change visualization utils and repurposing annotations gallery thumbnails

Rewrite draw_segmentation_masks and update gallery example to illustrate both instance and semantic segmentation models (#3824)