net-mgmt/zabbix6-*: Add CPE information

This is the intended mapping between port and CPE_VENDOR:CPE_PRODUCT

net-mgmt/zabbix5-agent zabbix:zabbix-agent
net-mgmt/zabbix6-frontend zabbix:frontend
net-mgmt/zabbix6-java zabbix:zabbix
net-mgmt/zabbix6-proxy zabbix:zabbix
net-mgmt/zabbix6-server zabbix:zabbix_server