They are safe, since they use the rust `std::env` stuff. Making them
safe lets downstream to determine that `std::env` is used and not the
`libc` env manipulation routines, which are unsafe.
The utils in this module should help the users to activate the windows
they create, as well as manage activation tokens environment variables.
The API is essential for Wayland in the first place, since some
compositors may decide initial focus of the window based on whether
the activation token was during the window creation.
Fixes#2279.
Co-authored-by: John Nunley <jtnunley01@gmail.com>