Bug 33371: Add 'koha-common.service' systemd service

Bug 33371: Add 'koha-common.service' systemd service

to test

- install current package
- note following $message on install
 'Failed to enable unit: Unit /run/systemd/generator.late/koha-common.service is transient or generated.'

- apply patch, build package, install new package
- note $message is gone! :)

- test koha-common.service
   # systemctl start  koha-common
   # systemctl status koha-common | grep running
     Active: active (running) since Sun 2023-04-02 00:27:31 NZDT <<<

   # systemctl stop  koha-common

   # systemctl status koha-common | grep dead
     Active: inactive (dead) since Sun 2023-04-02 00:25:34 NZDT <<<

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>