Enhance interface filtering and ensure uniqueness in netifyd configuration

[stephdl]

Improve the filtering of network interfaces by excluding specified patterns and ensure that internal and external interfaces are unique and sorted in the netifyd configuration.

#929

we can remove by the cli some interface (we look by startswith, so wg == wg*

• how to add an exclusion list

uci add_list netifyd.@netifyd[0].exclude='eth1'
uci add_list netifyd.@netifyd[0].exclude='tun'
uci add_list netifyd.@netifyd[0].exclude='wg'
uci commit netifyd

• how to add and remove item of the exclusion list

uci delete netifyd.@netifyd[0].exclude='eth1'
uci add_list netifyd.@netifyd[0].exclude='eth2'
uci commit netifyd

• how to remove completely the exclusion list

uci delete netifyd.@netifyd[0].exclude
uci commit netifyd