Restore Focus Widget in the GUI

[retiutut]

Is your feature request related to a problem? Please describe.
No.

Describe the solution you'd like
Restore the Focus widget using information from BrainFlow metric. Front end can remain the same for now. Important thing is to have a Focus widget with modest accuracy.

Restore Focus Widget output to the Networking widget for all networking modes.

Describe alternatives you've considered
This was removed as per a team decision related to the accuracy of the old Focus widget.

Additional context
The backend work for this issue has been completed! BrainFlow now has a metric that uses a simple classifier. 🛠✅

Need to update Docs also once this is coded and tested in the GUI. Specifically, the GUI Widget Guide.

[retiutut]

• Make new widget
• Make enums/functions for dropdown configurations
• Get metric data from BrainFlow
• Include channel select bar in the widget
• Add output to networking widget for all protocols that outputs the same as the old widget
• Update GUI Widget Guide Doc or any other references to the Focus widget in the GUI

[retiutut]

Add output to networking widget for all protocols that outputs the same as the old widget

No guarantee here. Going to do what seems simplest.

[retiutut]

Keeping the output of the Focus Widget Datatype to 1's and 0's, to make this easier for children and students to learn about binary, rather than expecting ALL users to code a threshold on the other end of the networking stream. Threshold can be set via the new Focus Widget.

[retiutut]

With the new Focus widget, it is still possible to "trick" the algorithm using synthetic data mode and perfect Alpha waves generated on Channel 2.

[retiutut]

Last task is to update the official OpenBCI Documentation.

I should also update the Instructable I made: https://www.instructables.com/Send-Focus-Data-From-OpenBCI-GUI-to-Arduino/

I'm happy to keep the same Arduino code to make the above work.