fix: populate reception_sequence_number and advertise sequence number features (backport #920)

[mergify]

Description

rmw_feature_supported currently returns false for both RMW_FEATURE_MESSAGE_INFO_PUBLICATION_SEQUENCE_NUMBER and RMW_FEATURE_MESSAGE_INFO_RECEPTION_SEQUENCE_NUMBER, causing rclcpp to skip populating these fields in rclcpp::MessageInfo entirely. Additionally, reception_sequence_number is always set to 0 with a TODO comment at both take sites.

The fix:

• Flips rmw_feature_supported to return true for both sequence number features.
• Adds a std::atomic<uint64_t> reception_sn_ counter to SubscriptionData, initialized to 0. Each call to take_one_message or take_serialized_message increments it with fetch_add(1, std::memory_order_relaxed) and assigns the pre-increment value to message_info->reception_sequence_number.
• publication_sequence_number was already populated from the attachment; no change needed there.

The attachment wire format (sequence_number | source_timestamp | source_gid) is unchanged — this fix is purely in the subscriber-side bookkeeping.

Closes #907
Closes #906

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This is an automatic backport of pull request #920 done by [Mergify](https://mergify.com).