Add cask avast-secureline-vpn

[gtmgianni]

I can't get the uninstall script to show me its arguments (if it has any), and additionally the user needs to restart their system immediately after the uninstall (because the script launches the GUI uninstaller, there is no other option for the user). Also, I included a commit in this pull request which changes the cask avast to avast-mac-security to avoid confusion between the two casks.

[gtmgianni]

Additionally, the zap stanza cannot be executed because it always first runs the uninstall sequence, which will either result in the computer having to be restarted after uninstallation, or throwing up an error because the cask is already uninstalled and the uninstaller no longer exists. Either way, the zap stanza is not run.

[gtmgianni]

I assume this behaviour is intentional, but if a user runs the zap command and the uninstall stanza fails (for whatever reason), the zap command is not executed afterwards. This issue occurs with the cask trusteer-rapport also, and means it is impossible for me to run the zap command.

[vitorgalvao]

This is a wrong use of uninstall script:. Like you mentioned, this is not a script but a GUI. Please remove it. Also see #24377.

[gtmgianni]

Actually, don't bother answering my other query @vitorgalvao, I've just realised the reason I'm having issues with zap.
zap is designed to be run instead of uninstall if you want a more thorough uninstallation, right? I've been using zap as a sort of "cleanup" command for cleaning up files after uninstallation, rather than as an "uninstall" command in its own right. Just using zap instead of uninstall fixes the problems I was having with trusteer-rapport and this new cask.