30s is apparently not enough on the runners.

This is intended as replacement for the NotifyFoo methods. libei
provides a more flexible and powerful method of sending input events to
the compositor.

A new method ConnectToEIS requests a file descriptor from the compositor
which can then be plugged into libei.

Once established, the communication between compositor and application
is direct, without the need to go through the portal process(es).

To avoid ambiguities between NotifyFoo and input events sent via libei,
any application that uses an EIS connection may not use the NotifyFoo
methods.

Co-authored-by: Olivier Fourdan <ofourdan@redhat.com>

The check_notify() helper returns false for a number of reasons -
session in the wrong state, using EIS when a Notify method is called,
etc. Adjust the error message a bit to be more generic.