feat: expose replicated_from proto field to Message

[BewareMyPower]

fixes #569

[Copilot]

Pull request overview

This PR exposes Pulsar’s replicated_from message metadata through the public C++ Message API and the C client wrapper, enabling consumers to detect geo-replicated messages (per issue #569).

Changes:

• Add Message::getReplicatedFrom() and a corresponding C API pulsar_message_get_replicated_from().
• Add C++ and C unit tests that validate access to replicated_from metadata via a test-only PulsarFriend hook.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
tests/MessageTest.cc	Adds a unit test for the new C++ replication accessor.
tests/c/c_MessageTest.cc	Adds a unit test for the new C replication accessor.
lib/Message.cc	Implements Message::getReplicatedFrom().
lib/c/c_Message.cc	Implements pulsar_message_get_replicated_from().
include/pulsar/Message.h	Declares the new public C++ accessor.
include/pulsar/c/message.h	Declares the new public C accessor and documents its lifetime.

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