GitHub to Linear per delucis

This extension makes it easier to view and create Linear issues associated with GitHub issues and PRs while browsing on GitHub.

- It injects an “Add to Linear” button in every issue and PR on GitHub — quickly create a new Linear ticket which links back to the PR or issue you want to track.
- Shows information about associated Linear issues in the sidebar of GitHub issues and pull requests.
- Shows linked Linear issues in GitHub issue and PR lists.