Title: [enhancement] Add MySQL client/server protocol layer in scapy.contrib (MVP)

Hi Scapy maintainers,

I would like to contribute a new protocol module for MySQL in scapy.contrib to simplify parsing and crafting MySQL packets during analysis and testing.

Reference style I plan to follow:

• scapy/contrib/postgres.py
• Existing UTScapy contrib tests in test/contrib/*.uts

Motivation

• MySQL is common in lab traffic and security assessments.
• Having native packet classes would make dissections and crafted exchanges easier than manual byte handling.
• A contrib module seems appropriate as a first step before considering broader scope.

Proposed scope (MVP)

• Add scapy/contrib/mysql.py with:
  • MySQL packet header (payload_length on 3 bytes + sequence_id)
  • Initial Handshake (Protocol::HandshakeV10) parsing/building
  • Handshake Response (client) basic parsing/building
  • Core server responses: OK_Packet, ERR_Packet, EOF_Packet
  • COM_QUERY packet support
  • TCP binding on port 3306
• Add regression tests in test/contrib/mysql.uts with deterministic byte fixtures.

Out of scope for MVP

• Full command set coverage
• Full capability/auth plugin matrix
• Compression protocol and all optional extensions
• Complex session reassembly edge cases beyond base packet framing

Design goals

• Keep API Scapy-like and minimal.
• Avoid external runtime dependencies.
• Keep implementation and tests small and reviewable.

Questions for maintainers

• Is scapy.contrib the right location for this protocol initially?
• Is the MVP scope above acceptable for a first PR?
• Any preferred naming conventions for MySQL packet classes/fields before implementation starts?

If this direction looks good, I will open a first Draft PR with the MVP and UTScapy tests.