feat: Add GitHub repository import

[Nithishvb]

trafficstars

Description

This PR introduces support for importing GitHub repositories directly as templates into CodeSandbox sandboxes.

Related Issues

Type of Change

• [] Bug fix
• [x] New feature
• [ ] Documentation update
• [ ] Release
• [ ] Refactor
• [ ] Other (please describe):

Testing

Screenshots (if applicable)

Additional Notes