Reorder protocol class members to the member-order convention #2490

Reorder protocol class members on main to the member-order convention. Ruled by the owner: HTTP v1 is a violation; dunders (__init__, __new__, __post_init__, __index__, __length_hint__, and the rest) are Data Models; the old protocols (IPv4, TCP, UDP, ARP, Ethernet, IPv6) are the reference.

Order inside a protocol class body: properties, public methods (id, read, make, register_*), dunders (Data Models), then utilities (_read_xxx before its _make_xxx).

Landed violations (ref: audit on 545ad0ca7): application/application.py, application/httpv1.py (HTTP), application/httpv2.py, application/ospf.py, application/ssl.py, data/application/httpv2.py, internet/esp.py, internet/hip.py, internet/ipv6_route.py, internet/ipx.py, internet/mh.py, misc/pcap/frame.py, misc/pcap/header.py, misc/pcapng.py, protocol.py (ProtocolBase), schema/misc/pcapng.py, schema/schema.py, transport/sctp.py.

Open PR-only violations are fixed by each PR's own rework (#2444, #2446, #2465, #2466).

Mechanical reorder only; no behaviour change. Split by file group, one PR per group.