allow to use mqtt inside shared worker

[nosovk]

Currently Shared Worker allowed to create ws connection. Even more - it persists between page reloads, also it's shared between tabs. Looks great!
But there are few problems.

1. to connect to shared worker we also have to use simplified messaging (which is ideal for MQTT)
2. to run MQTT in shared worker we probably need lots of efforts from MQTT.js There is old abandoned version in official repo - https://github.com/mqttjs/mqtt-worker - currently it's not usable.

In my opinion the best solution is to setup internal mqtt between window and shared worker. And then shared worker could retranslate those messages to external broker.
Also in that way we can communicate between tabs using shared worker like small internal broker inside browser.

But main problem is running mqtt js in shared worker.

[nosovk]

found https://github.com/cotonic/cotonic
It probably does what we need, but codestyle is bit weird.