User units in needrestart-session

[Vladimir-csp]

Please add the same functionality that exists in main needrestart to needrestart-session, that is matching processes with user services (via systemctl --user) and providing a checkboxed list for restarting.

For example, services could be listed first, with checkboxes, then other processes grouped by scopes, just for info (although processes in init.scope can be reexecuted with systemctl --user daemon-reexec), then processes from user's session scopes (only main systemctl will show those).