logind: state serialization fixes (#37555)

Turns out our escaping was really broken when saving/restoring
session/seat/user state. Let's fix that.

diff --cc src/basic/env-file.c
Simple merge

diff --cc src/login/logind-inhibit.c
Simple merge

diff --cc src/login/logind-seat.c
Simple merge

diff --cc src/login/logind-session.c
Simple merge

diff --cc src/login/logind-user.c
Simple merge