Display commit sha on app UI

[Bisaloo]

A simple gert::get_commit_info() is causing issues when deploying on shinyapps.io because the .git/ folder is not copied.

A workaround would be to create a file / an env var with the current commit in the deploy-rsconnect workflow but then, we would have issues when deploying locally.

It may be time to use staging vs prod environments: https://kellobri.github.io/shiny-prod-book/connecting-to-data-in-production.html#the-config-package