Improvements in get/set socket options

[josesimoes]

Description

• Rework GetSocketOption to correctly return correct type with several SocketOptionName.
• GetSocketOption can now return value for SocketOptionName.DontLinger.
• Rewrote some parts of the documentation to make it clearer.
• Add some unit tests for socket options.

Motivation and Context

• Addresses Review socket linger implementation Home#937.

How Has This Been Tested?

• Unit tests and network sample.

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)
• Config and build (change in the configuration and build system, has no impact on code or features)
• Dependencies (update dependencies and changes associated, has no impact on code or features)
• Unit Tests (work on Unit Tests, has no impact on code or features)
• Documentation (changes or updates in the documentation, has no impact on code or features)

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.