Bugfix: Invalid IPv6 addressdetection and improve IPv4 address detection in f_network...

Bugfix: Invalid IPv6 addressdetection and improve IPv4 address detection in f_network_is_ip_address().

The `f_network_is_ip_address()` is not properly identifying bracketed IPv6 addresses.

Digits to the left of double colons `::` should be supported.
The forward slash `/` should be allowed after double colons `::`.
Ending in a double colon `::` is in fact valid in situations, such as with `::/0`.

Make the IPv6 logic easier to follow by adding additional comments.
Also rename `count` to `digits` to further make the code logic more understandable.

Improve IPv4 detection by checking if the number is between 0 and 255, inclusively.

Add more unit tests to better catch the newly identified and now resolved problems.
Update unit tests to use the newer `macro_f_string_static_t_initialize_2()` instead of `macro_f_string_static_t_initialize_1()`.
Add additional comments to help identify rows.