THRIFT-6078: Send SNI from Ruby SSL clients

[kpumuk]

Some TLS terminators, proxies, and load balancers require SNI in the ClientHello to route the connection or select the correct certificate. Ruby clients previously performed post-handshake hostname verification, but did not send a server hostname during the handshake.

Ruby Thrift::SSLSocket now sets the OpenSSL server hostname before starting the TLS handshake, allowing clients to send SNI for hostname-based SSL connections.

It also adds an optional server_hostname: override for cases where the client connects to one address but needs to indicate and verify a different DNS name.

• Did you create an Apache Jira ticket? THRIFT-6078
• If a ticket exists: Does your pull request title follow the pattern "THRIFT-NNNN: describe my issue"?
• Did you squash your changes to a single commit? (not required, but preferred)
• Did you do your best to avoid breaking changes? If one was needed, did you label the Jira ticket with "Breaking-Change"?
• If your change does not involve any code, include [skip ci] anywhere in the commit message to free up build resources.

[Copilot]

Pull request overview

This PR updates the Ruby Thrift::SSLSocket transport to send SNI (Server Name Indication) during the TLS handshake by configuring the OpenSSL socket’s server hostname before connecting, and adds an optional server_hostname: override to support connections where the dialed address and expected DNS name differ.

Changes:

• Set OpenSSL::SSL::SSLSocket#hostname= (when appropriate) prior to the TLS handshake so Ruby clients emit SNI.
• Add server_hostname: (defaulting to host) and use it for hostname verification, while avoiding SNI for IP-literal hostnames.
• Extend Ruby specs to cover SNI behavior, server hostname override, and explicit SNI disablement.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
lib/rb/lib/thrift/transport/ssl_socket.rb	Adds server_hostname support and configures SNI/verification behavior for Ruby SSL sockets.
lib/rb/spec/ssl_socket_spec.rb	Updates and adds tests validating SNI setting, hostname override behavior, and SNI suppression for IP literals / explicit disablement.

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