Add a VMware Item Key for the serial number aka "vmware.hv.hw.serialnumber"

We use Zabbix 3.2.4 and tested the VMware Template against our vCenter Installation. So far I like the items we can gather very much, but I miss the serial number of the hardware. So far we get 8 different item keys for the hardware, but the serial number is missing.
There should be and item key similar to "vmware.hv.hw.model[<url>,<uuid>]" which gets the serial number. The VMware vCenter itself is aware of the serial number, so when you get the hw modell, it should be no problem to get the serial number as well. This would be great to get this information faster.

See a screen of vcenter attached, where you see the all information all already there.