Fix in KNXnet/IP layer (KNX addresses handling)

[claire-lex]

This PR introduces a few changes to the KNXnet/IP layer, last updated in 2021:

• Fix validation and support issues on KNX individual addresses and KNX group addresses (see below)
• Add a few recognized KNX codes and supported types for MultipleTypeFields in complex packets
• Add basic and KNX address-related unit tests

I made the PR mainly to fix issues when building packets containing individual address (format 1.1.1) or group address (format 1/1/1) fields. The layer only supported either individual address or group address in a field, but some fields (for instance, in cEMI blocks) can take both formats. For instance, the code below used to raise a ValueError and is now valid.

test_addr = CEMI(message_code=0x11) # L_Data.req
test_addr.cemi_data.address_type = 0 # Individual address
test_addr.cemi_data.destination_address = "1.1.1"

[guedou]

Thanks for the PR. Could you fix the flake8 issues at https://github.com/secdev/scapy/actions/runs/13262979518/job/37023594039?pr=4663 ?