Replace WIN32 with .NET tool for nanoCLR in test executor

[josesimoes]

Description

• Rework test execution to use nanoCLR .NET tool instead of WIN32 build for executing tests.
• Add new setting to nano runsettings to be able to specify a local instance of nanoCLR DLL.
• Rename CheckAllTests to ParseTestResults (for clarity).
• Remove target required to install WIN32 CLR.
• Remove dependency of WIN32 CLR nuget, reference and packaging in NuGet.
• Update PoC test project accordingly.

Motivation and Context

• Need to drop WIN32 version in favour of .NET tool to allow deprecating it and running the test framework on all platforms.

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 with code or algorithm)
• New feature (non-breaking change which adds functionality to code)
• 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 (add new Unit Test(s) or improved existing one(s), 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 (only if there are changes in source code).
• My changes require an update to the documentation (there are changes that require the docs website to be updated).
• I have updated the documentation accordingly (the changes require an update on the docs in this repo).
• I have read the CONTRIBUTING document.
• I have tested everything locally and all new and existing tests passed (only if there are changes in source code).
• I have added new tests to cover my changes.

[Ellerbach]

Looks good all up! minor comments.