wayland: Fix handling of activation-token in org.freedesktop.Application requests
At the moment, GTK applications search for "desktop-startup-id" in the platform data on Wayland , but desktop environments such as plasma set "activation-token" property instead as indicated in the spec:
activation-token: This should be a string of the same value as would
be stored in the XDG_ACTIVATION_TOKEN environment variable, as specified
by the XDG Activation protocol for Wayland.
https://specifications.freedesktop.org/desktop-entry-spec/desktop-entry-spec-latest.html#dbus
Draft: it looks like I need to overwrite add_platform_data and after_emit too
Edited by Vlad Zahorodnii