[session] Replace user-session@.service with a config for user@.service
[session] Split user session startup service to two separate services
Fix path of environment variables & some packaging fixes

[packaging] Fix rpm file list
[packaging] Add set-boot-state binary
[packaging] Fix start-user-session permission to be executable by user
[session] Make start-user-session.service shutdown friendly
[session] Fix init-done ordering: start-user-session@USER.service is now start-user-session.service
Use more clear copyright notices, to separate it from Jolla contributions
[packaging] Describe why default.target for user is not used anymore
[packaging] Remove killx, not used anymore. Remove Xorg subpackage (containing only xorg.target) altogether.
[packaging] Remove correct-users script, not needed for new images
[packaging] Mark package as noarch, since it doesn't contain any binaries