Fix issues with wireless config save/load

[josesimoes]

Description

• The string fields weren't being properly handled
• Add constructors to config base classes to ensure that the byte arrays size match
• Minor improvements in WPF test app

Motivation and Context

• Fixes issue with storing/getting wireless config block to/from device

How Has This Been Tested?

• WPF test app

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: josesimoes jose.simoes@eclo.solutions

[nfbot]

Hi @josesimoes,

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

A human will be reviewing it shortly. 😉