fix(Tornado): Fix SSL client certificate authentication with M2Crypto

[fstagni]

The Tornado server was failing to extract client certificates during TLS handshake, resulting in 401 Unauthorized errors. The root causes were:

1. M2IOStream.initialize imported m2_wrap_socket at module load time, so late patching didn't affect the bound reference
2. The peer certificate was lost when close_fd() cleared the socket after handshake completion
3. read_from_fd returning 0 was treated as EOF, causing premature stream closure

Fixes applied:

• Replace M2IOStream.initialize with version that imports m2_wrap_socket at runtime
• Patch _do_ssl_handshake to store peer cert/chain before socket cleanup
• Patch read_from_fd to return None instead of 0 to prevent premature closure
• Patch get_ssl_certificate/get_ssl_certificate_chain to use stored cert
• Patch HTTPServerRequest to delegate to stream's certificate methods

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[chrisburr]

This definitely isn't the solution. We'll need another tornado_m2crypto release for the real fix.

[chrisburr]

I think the real fix is DIRACGrid/tornado_m2crypto#10