Feature: end to end delivery

[VivekPipaliya23]

Proposed Changes

Introduced a delay_qos1_puback setting, allowing operators to choose deferred QoS1 acknowledgements. The MQTT FSM now tracks this setting, sending immediate PUBACKs when disabled, or delaying them until subscriber PUBACKs are received when enabled. When delayed, PUBACKs are handled sequentially and sent back to the originating ranch process after the subscriber ACKs, maintaining the default behavior.

Types of Changes

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• Bugfix (non-breaking change which fixes issue #XXXX)
• New feature (non-breaking change which adds functionality)
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Further Comments

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considered, etc.

[dhruvjain99]

Will it be right to exit or terminate publisher process if subscriber sends a wrong mid?

[VivekPipaliya23]

Avoided exit and added error log.

[dhruvjain99]

This can be part of maybe_send_puback

[VivekPipaliya23]

done