Major rework on SerialDevice and Engine

[josesimoes]

Description

• Partial rewrite on the connect device workflow
• Improvements on the disconnect device worfflow
• SerialPort now has Read and Send cancellation tokens to improve cancelling of pending I/O operations on device disconnect
• Valid nanoDevice checking after complete devices enumeration is now carried as a separate task and not part of handler anymore
• Remove unused flag for autoreconnect on serial device event handler
• DebugEngine propery in NanoDeviceBase doesn't auto-instanciate anymore
• NanoDeviceBase now has a CreateDebugEngine
• Engine doesn't offer a Disconnect method anymore
• Engine doesn's start background processor on constructor anymore becuase the associated nanoDevice might not be connected at that point, instead is started an ConnectAsync if needed
• Engine.RebootDevice doesn't force device disconnection anymore, there are devices that do not require that and even behave oddly if this is forced
• Clean up code and remove several debug output messages
• Update WPF test app

Motivation and Context

• Improves connect/disconnect/reconnect workflow for USB serial devices

How Has This Been Tested?

Screenshots

Types of changes

• Improvement (non-breaking change that improves a feature, code or algorithm)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

Signed-off-by: José Simões jose.simoes@eclo.solutions

[nfbot]

Hi @josesimoes,

I'm nanoFramework bot.
Thank you for your contribution!

A human will be reviewing it shortly. 😉