Add Epoch to Gnome Launcher

[lhstrh]

Like so: https://askubuntu.com/questions/112186/how-do-you-create-a-custom-application-launcher-in-gnome-shell

[cmnrd]

We do this already for our AUR packages. Here is the link to the desktop file: https://github.com/lf-lang/pkgbuilds-lingua-franca/blob/main/epoch-bin/epoch.desktop

For the installer script, we would only need to adjust the bin path and the icon path according to the actual install location.

BTW, this also works on other desktop environments like KDE ;)