feat(api): use gosling server instead of HiGlass server for gene search

[sehilyi]

Fix #
Toward #

Change List

• Replace the HiGlass server with the Gosling server for supporting gene search APIs
  • The Gosling server has three assemblies supported, so I replaced the HiGlass server for three assemblies: https://server.gosling-lang.org/api/v1/tilesets/?limit=99999&dt=gene-annotation

Checklist

• Ensure the PR works with all demos on the online editor
• Unit tests added or updated
• Examples added or updated
• Documentation updated (e.g., added API functions)
• Screenshots for visual changes (e.g., new encoding support or UI change on Editor)