Installer - Uninstall without admin and should check if installed already

[willwade]

• Need to integrate this kind of logic - https://nsis.sourceforge.io/Auto-uninstall_old_before_installing_new - basically if you have it installed already and try and install it seems to work but it won't because the service is running and then files are being accessed. It basically makes a right mess
• Uninstalling is not set to run as admin. I dont get why - see http://forums.winamp.com/showthread.php?p=3221719#post3221719 . Because of this it never uninstalls - unless the user manually elevates the uninstall package
• As a bonus it would be nice if the correct shortcuts are made on Windows 10/11. You dont see it in the app list reliably. No idea why
• uninstaller not being recognised in add/remove apps. Or at least I don't think so

[willwade]

Just realised our build script is super hacky. We should be doing this rather than copying all the files into one: https://www.zacoding.com/en/post/pyinstaller-create-multiple-executables/