Hotfix: 2.4.2

Issue tracker for 2.4.2

- [x] Upload attachment ID not actually saved #340
- [x] Replace "load_template" with "require" #335 
- [x] Auto-Fill Option IDs in the Theme Options UI Builder #326
- [x] Option Tree experience with nginx server! #337 
- [x] Cannot see settings in admin panel #338 
- [x] Feature Request: Allowing textarea via filter #342