Feature Request: add symbolic link functionality in the UI

### What

I would like to be able to add a symbolic link in the Studio user interface.

### Why

Allows for support of plugins and/or themes that are being locally created.
This will enable faster theme & plugin development without the user needing to know how to use/implement symlinks in command line.

### How

1. On the Studio Overview tab, add new sections for "Plugins" and "Themes"
2. Add buttons for "Add Plugin Folder" and "Add Theme Folder" (one per section)
3. When clicked, open Explorer/Finder and allow the user to select a folder.
4. This will then be parsed for a valid theme/plugin structure and, if valid, then added as a symlink in the OS between the target folder and the Studio folder.