internal checks for Zabbix proxy

Internal checks for Zabbix proxy is useful for checking performance of the Proxy

• proxy[log]
• proxy[process] (internal process busy rates)
• proxy[queue] (same as server queue)
• proxy queue (amount of values, not synced to the server yet)
• proxy[requiredperformance]
• proxy[wcache]
• proxy[rcache]
• amount of hosts monitored (calculated by the server)
• amount of items monitored (calculated by the server)