Update texture atlas with thumbnails for off-chain emotes (bevy-ui-scene PR #62)

## Context
The bevy-ui-scene PR #62 (new-off-chain-emotes branch) adds support for new off-chain emotes but still needs the texture atlas updated with the proper icon thumbnails.

The PR is currently blocked by:
- Merge conflicts (branch is ~1 month old)
- Missing texture atlas update

## Tasks
- [ ] Resolve merge conflicts in the new-off-chain-emotes branch
- [ ] Update texture atlas with thumbnails for the new off-chain emotes
- [ ] Test the icons display correctly in the UI

## Related
- bevy-ui-scene PR #62: https://github.com/dcl-regenesislabs/bevy-ui-scene/pull/62
- bevy-explorer issue #480: https://github.com/decentraland/bevy-explorer/issues/480

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_Requested by Pablo.​dcl.​eth via Slack_
_Note: Please assign to Pablo once created (GitHub username to be confirmed)_