Adds reload service and fixes MQTT not enabled at startup

[danielbrunt57]

• Added hass_agent.reload service
• Checks for MQTT integration enabled and the client is available at startup

[amadeo-alex]

Copy paste message incoming :D
In case of question I'll of course answer separately.

Thank you very much for the PR, we need to fix this PR so it will actually appear as forked from the original repository by LAB02. I don't like the fact that it's not clear that it's a forked repository. I've already created a repository with all PRs that were created to this repository - https://github.com/amadeo-alex/HASS.Agent-Integration/tree/prs-merge - what I'll most likely do is to rename this one, fork the original one properly and then merge the "prs-merge" to that. Of course as it already is with "prs-merge", your contribution will be visible and in addition mentioned in the main PR to the organisation repository.

Please let me know if you'd have anything against it :)