luci-base: add hostport and ipaddrport validation types

luci-base: add hostport and ipaddrport validation types

Add two new types 'hostport' and 'ipaddrport' to validate strings in the form
'sub.example.org:1234' and '0.0.0.0:80'. The 'hostport' accepts hostnames or
IP addresses followed by a colon and a port number while the 'ipaddrport' type
accepts numeric IP addresses only, followed by a colon and a port.

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>