Restricted Gameplay Tags cannot be added

The Gameplay Tags settings have the option to set up restricted tags as described in the documentation. Prior to 5.3, the UI correctly supported creating new restricted tags as described in the old documentation. When the gameplay tag creation UI was redone in 5.3, it broke the ability to create new restricted gameplay tags in the UI.

The primary issue is with SAddNewGameplayTagWidget as it does not know how to create restricted tags and is hardcoded to use the normal tag sources. To fix this issue, the add tag UI needs to be updated to handle selecting and adding to restricted tag sources

1. Open QAGame or another test project, make sure it is connected to revision control
2. Open the Gameplay Tags project settings
3. Expand the Advanced section in Advanced Gameplay Tags
4. Click the + next to Restricted Config Files to add a new config file for restricted tags
5. Enter TestConfig.ini as the name, leave the owner as your login name
6. Click Manage Restricted Gameplay Tags to open the tag viewer
7. Click the Plus to add a new tag and look at the list of possible tag sources

Expected behavior:

The tag source should include TestConfig.ini as it is a source for restricted tags.

Broken behavior:

The tag sources list will only include the normal tag sources, and trying to add a new restricted tag will instead add a normal gameplay tag or fail