Update .NET/C# API binding to support FDC3 API Metadata as a required feature

## Enhancement Request

FDC3 API Metadata is new feature intended for the FDC3 3.0 release, which resolves issues:
- #735
- #1290

The changes were implemented for Web browsers in PR:
- #1728 (merged)

And forms the base for the FDC3 Security features being implemented for 3.0:
- #1492
- #1886

This issue requires that the additions to the API are translated into the .NET/C# API binding for FDC3.

@bingenito

Start with the .NET/C# API binding and compare its current API surface with the FDC3 API Metadata additions from merged PR #1728. Review related issues #735, #1290, #1492, and #1886 for requirements and dependencies. Done means the API Metadata feature is translated into the .NET/C# binding as required for FDC3 3.0.

Written by the indexing model from the issue text.