Automatically add environments to the launcher menu.

[shawnbrown]

Some users might like to have new environments automatically added to their EnvLauncher icon's context menu.

I'm filing this issue because I think it's natural for a user to request something like this but there are limits to how it can be implemented. Desktop environments are not consistent in how they refresh application icon updates while a session is running and an implementation that provides inconsistent results is not going to be satisfying.

I think that a decent compromise would be to create a service that scans for new environments when a session starts (with a systemd unit). If there is interest for something like this, I'm open to exploring a solution in the future but it's not going to be part of a 1.0 release.