Use the new updater

[LagradOst]

This searches for updates using the new updater, as well as moves the viewmodel to the shared scope. '

Unfortunately kotlin is a bit weird about val on data classes in a different project, so the old code actually gives error if we move it without val dialog = updaterState.dialog.

[fire-light42]

The markdown parsing is not very robust, but it is sufficient for updates. I would recommend updating (creating tests) it if its used to render user-provided text (plugins).

Otherwise everything looks good and works well. The only foreseeable issue is constant update popups if we delete a version (since its a mismatch).