RecipeAtlas Management Screen

[bigbass1997]

Create a GUI which allows the user to select which recipe atlas to use. The atlas is the JSON file which contains all of the recipes that NEP uses.

The GUI should sync with all of the available download mirrors in order grab all available atlases for download. It should also list all atlases that are available locally, while making sure there aren't duplicates. As in, if the user has already downloaded an atlas, then it should indicate such a situation for that particular atlas.

It will be safe for now just to compare the filenames (minus extension). In the future, it may be helpful to implement file hashing to better compare local vs remote files.