[Feature Request] - Improved GitHub integration shortcuts

[stuartcamerondeakin]

A few small(ish) GitHub integrations that would greatly improve workflows for people working on large teams.

1. In the list of branches, if there is a pull request for that branch on GitHub show the PR number next to the branch, with a right-click option to open that PR in the browser
2. If diffing a file in a PR, add a right click Reveal line in GitHub PR #xxx option to open that change in GitHub so you can easily add a comment to the PR review
3. Add a Reveal line in GitHub option to any line either in a diff or viewing a file from the file tree that will navigate to that line of code on GitHub, allowing you to add a permalink that can be shared with other team members for discussion.