generate_config: Move filters to external library

generate_config: Move filters to external library

Clean and isolate main script logic from custom filters by moving
all them to a external library file.
Library has a function to load all the existing filters at once.

New enhanced IP handling custom filters:
 - ipnet_hostaddr
 - ipnet_hostmin
 - ipnet_hostmax
 - ipnet_broadcast
 - ipnet_netmask
 - ipnet_contains_ip
 - ipnet_contains_iprange
 - ipnet_range_size

ipnet filters work with proper IP network with prefixlen mask,
ensuring consistent IP calculations and error handling.

Previous IP handling filters should be deprecated.

Change-Id: I83c41d7ad3c6bd1d9df1deca6cc5b9d2481ecf52
Signed-off-by: Guillermo Herrero <guillermo.herrero@enea.com>