Пакет service: Информация

- preun_service: added chkconfig call in systemd case (closes: #30165).
- service: added legacy-actions support (closes: #29925).
- sd_booted: synced systemd check with libsystemd.

- service: use is-active as a closer systemd equivalent of
  sysvinit status (closes: #30034).

- Implemented systemd-only service support in {post,preun}_service
  (closes: #27390) and native support of systemd services.
  Due to systemctl limitations, when systemd is active,
  post_service will no longer be able to enable sysv-only services.
- Added /sbin/sd_booted utility.