hidden dependencies on private functions

[pawelru]

Please remove / rethink all the hidden dependencies on private functions defined elsewhere. This kind of work-around of dependencies specifications are hard to identify and maintain.

https://github.com/insightsengineering/teal/blob/8ab74927a9a603ea1fe5da6398e5d0a228ccfb46/R/zzz.R#L26-L34

Some of them already have a note that it's a temporary hack which is okey for now but the other part is missing.

This already hit us back: https://github.com/insightsengineering/teal/issues/908.