appimageTools.wrapAppImage: Fix passing arguments to wrapped executable
appimageTools.wrapAppImage: Fix passing arguments to wrapped executable

appimage-exec.sh parses its arguments with getopts, so we need to
delimit arguments intended for the wrapped executable with ‘--’, in
case some of them begin with ‘-’.

Without this fix, a wrapped application like Zulip Desktop can’t be
opened the normal way using the .desktop file, which includes
‘Exec=zulip --no-sandbox %U’ (as per the electron-builder default):

$ gtk-launch zulip.desktop
/usr/bin/appimage-exec.sh: illegal option -- -
Usage: appimage-run [appimage-run options] <AppImage> [AppImage options]
[…]

Signed-off-by: Anders Kaseorg <087231934ba8fcf78bc142ce37d193b895ac03c4@mit.edu>

NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs