ui: firwall: change icmp type selector to a combogrid

ui: firwall: change icmp type selector to a combogrid

The combogrid contains all valid icmp types that iptables accepts. In
addition to the names, the Type[/Code] value is shown as well. But
specifying Type[/Code] is not supported.

As the simple solution with setStore() does not work to change the
store for the combogrid, we simply have 2 different
ICMPTypeSelectors, one for IPv4, the other for IPv6, which are
switched depending on the specified protocol.

As disabled fields don't submit their value, we can keep the values
for the dport and both icmp-type fields when switching protocols.

Signed-off-by: Mira Limbeck <m.limbeck@proxmox.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>