HARP devices do not connect in embedded Unity workflows

[RoboDoig]

This probably applies to other Serial devices as well.

In a Bonsai workflow run from unity, HARP device nodes / associated branches will not throw errors, but no data will be received from them.

• Confirmed branch for the HARP device is alive using timeoutexception.
• Confirmed that other non-connected parts of the workflow are working as normal.

Culprit is likely to be DataReceived callback which is raised on a secondary thread and may not be accessible to Unity runtime.

[glopesdev]

Related issue in Unity discussions: https://forum.unity.com/threads/serial-communication-and-serialport-datareceived-event.139157/

If confirmed, we'd need to rethink how to workaround the integration.

[glopesdev]

Another related issue in unity bug-tracker: https://issuetracker.unity3d.com/issues/serialport-bytestoread-returns-null-reference?page=2#comments

An interesting comment can be found in the comment thread "Solved after set Script Runtime Version to Experimental (.Net 4.6 Equivalent)"