Demo upload system

Setup a system for automaticly uploading demo files to the web panel

List of things to look into

• Demo size
• Upload on command
• Deleting files from sp
• Upload size, max body size and RAM usage [web panel] => move to documentation
• Authentication for contextless upload

List of things todo

• CVar bool for uploading after demo write
• CVar bool for deleting demo after upload
• Regular Upload function
• Upload command
• Demo delete logic