cooms/ebusd: update to the v21.2 (Plum) Release

• added trailing wildcard to "ebuspicloader" port
• added more startup logging
• added colon as additional separator for "--log" option
• fix for publishing several MQTT updates at once
• optimized keep alive option for net devices
• fix for duplicate entry "minarbitrationmicros" in HTTP GET
• fix for extra send retry
• fix for newer compiler versions
• fix for potential illegal string usages
• fix for named net device not being resolvable during startup