openvpn: T1617: T1632: support quotes in openvpn-option
openvpn: T1617: T1632: support quotes in openvpn-option

The following CLI command can be used to add a raw option to OpenVPN
which requires quotes:
 > set interfaces openvpn vtun10 openvpn-option 'push &quot;keepalive 1 10&quot;'

The resulting config file will then have the following set:
 > push "keepalive 1 10"

vyos/vyos-1x,vyos/vyos-1x,vyos/vyos-1x,vyos/vyos-1x