gh-98078: fix asyncio SSL transports not sending the fatal TLS alert to the peer when the TLS handshake fails

[kumaraditya303]

• Issue: asyncio SSL not sending TLS Fatal Alerts #98078

Fixes #98078

When an ssl.SSLError occurs on an asyncio SSL transport,
SSLProtocol force-closed the transport without flushing the outgoing
MemoryBIO, dropping the data OpenSSL left there for the peer: the
fatal TLS alert on handshake failure or on receiving invalid data, and
the close_notify alert on shutdown failure. The peer only saw the
connection abruptly closed with no way to tell why, while blocking
ssl.SSLSockets do send these alerts.

Fix this by calling _process_outgoing() before _fatal_error() on
the three SSLError paths (_on_handshake_complete(), _do_read(),
_do_shutdown()). For example, a server whose certificate is rejected
now gets SSLError: [SSL: TLSV1_ALERT_UNKNOWN_CA] instead of
ConnectionResetError, and a peer of a failed shutdown gets a clean
TLS EOF instead of a reset.

[bedevere-bot]

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