page_metrics_ui() still lives in closed-source version

[klmedeiros]

Currently if you try to create an app with the shinybones suite of packages (it + shinymetrics + tidymetrics) and you no longer have access to any of the closed-source packages some of these were developed from, you get warning and cannot create the app:

Warning: No function named page_metrics_ui can be found

I believe this is because page_metrics_ui() and its associated functionality still lives in the closed-source packages only. This will all have to be moved out to make things usable.