Various additions to plugin

[jessm33]

The following changes/improvements are included in this PR:

1. Allow the user to override the default MQTT client id. This is needed when multiple instances are connecting to one MQTT broker. Having multiple clients with the same id, will cause the clients with the same id to be disconnected form or denied login to the MQTT broker. Also the MQTT standard requires all clients to have a unique ID.
2. Set the retained flag on messages that are only sent on startup(config, systems, and recorders). This will tell the MQTT broker to retain the last message on each of these topics, so clients can get this information, if they weren't there to receive these messages when trunk-recorder starts up
3. Send the list of all of the recorders. This brings this plugin more in line with stat_server functionality.
4. Put the mqtt store folder in the configured captureDir, to allow for the store to be located in a location where disk writes are preferred, such as a ram disk like /dev/shm.
5. Allow building with the shared paho libraries such as those provided in Ubuntu 22
6. Add a Dockerfile to add this plugin to the trunk-recorder docker image.
7. Remove compiler warning based on (Multiple CMake fixes and version updates to resolve compiler warnings robotastic/trunk-recorder#738)

[robotastic]

Sorry it has taken me so long to merge! I missed the notification.