No functional changes intended.
This just replaces all calls to `PBONE_VISIBLE` and `EBONE_VISIBLE`
with appropriate functions.
In the case of editbones it is just the function that the macro already contained.
For pose bones, a new function was added that mirrors what the macro had.
Using a function will make it easier to change how selection is queried in the future.
part of #138482
Pull Request: https://projects.blender.org/blender/blender/pulls/138819
9ee5196db7