Add arbitrary JSON parsing as input for dashboard

[Miceuz]

Is your feature request related to a problem? Please describe.
I would like to use SerialStudio to visalize JSON data piping in via MQTT. I don't want to change JSON format just for SerialStudio. Now I have to change JSON format in my applications to either be less verbose by packing CSV into JSON or use SerialStudio JSON format that would litter my model I am transmitting with a view related stuff.

Describe the solution you'd like
Add a communication mode 'Arbitrary JSON'. JSON file editor would allow to enter JSONPath queries into the Frame index field. SerialStudio would plot results of JSONPath queries if they are numerical.

Describe alternatives you've considered
Another alternative is to wait for a first JSON packet and provide drop-downs in JSON editor populated with leafs of arbitrary JSON structure.

[txf-]

I would like to add that I would really love this. Just have arbitrary json messages and then have a config that plotted the elements you needed from the message.

Something like MQTT Explorer does.

With that you can just choose to plot any numeric value you select out of the received json messages. I would love to use Explorer, but that only works with MQTT, is abandonware and has a license incompatible with modification.