feat: Check for updates to the launcher itself

[psychedelicious]

Currently, the launcher checks for updates for the app but not itself.

At some point we will get the launcher set up to self-update but we might not get to that in the very near term.

Until that is set up, it would be nice if the launcher checks for updates for itself. It could use largely the same logic as the app update checking logic and link to the release page or docs.