Fix handling of visibility with nested OptionGroups.

[bob-wilson]

The visibility of OptionGroups is ignored if they are nested inside another OptionGroup. Instead of trying to filter groups when creating an ArgumentSet, use the OptionGroup's visibility to modify the arguments within the group.

Checklist

• I've added at least one test that validates that my change is working, if appropriate
• I've followed the code style of the rest of the project
• I've read the Contribution Guidelines
• I've updated the documentation if necessary