The clipboard= configuration file determines what clipboard manager should be
used, if xclip or wl-copy/wl-paste. The variable defaults to the value of
XDG_SESSION_TYPE which is considered a reliable method to determine what
graphical session is currently being used[1]
[1] https://unix.stackexchange.com/a/355476
The configuration is stored under ~/.config/imgbb_uploader.conf.
The file is simply sourced, so the configuration file can be
a shell script. It just needs to assign the required variables.
