Move ZabbixAPI core functions to own service.
Move ZabbixAPI core functions to own service.

alexanderzobnin/grafana-zabbix,alexanderzobnin/grafana-zabbix,xiaohuiz/grafana-zabbix,alexanderzobnin/grafana-zabbix,alexanderzobnin/grafana-zabbix,alexanderzobnin/grafana-zabbix,xiaohuiz/grafana-zabbix,alexanderzobnin/grafana-zabbix