MQTT 5: Subscription Identifier

[dmytro-landiak]

Pull Request description

MQTT 5 feature implementation - subscription id. https://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html#_Toc3901092 https://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html#_Toc3901117 https://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html#_Toc3901166

General checklist

• [x] You have reviewed the guidelines document.
• [x] Labels that classify your pull request have been added.
• [x] The milestone is specified and corresponds to fix version.
• [x] Description references specific issue.
• [x] Description contains human-readable scope of changes.
• [x] Description contains brief notes about what needs to be added to the documentation.
• [x] No merge conflicts, commented blocks of code, code formatting issues.
• [x] Changes are backward compatible or upgrade script is provided.

Front-End feature checklist

• [x] Screenshots with affected component(s) are added. The best option is to provide 2 screens: before and after changes;
• [x] If you change the widget or other API, ensure it is backward-compatible or upgrade script is present.

Back-End feature checklist

• [x] Added corresponding unit and/or integration test(s). Provide written explanation in the PR description if you have failed to add tests.
• [x] If new dependency was added: the dependency tree is checked for conflicts.