WIP: Re-Send historic data after reconnection

[sfeilmeier]

If connection between OpenEMS Edge and Backend is interrupted, the missing data should be resent to Backend, once connection is re-established.

This PR is Work-In-Progress to enable community engagement.

Previous try: #1177

Discussion in OpenEMS Community: https://community.openems.io/t/influxdb-data-queueing/1057/9