Combine client-net and commons-net repositories into single one client-dotnet

[nvborisenko]

We have 2 repos, would be better to have single repo. It will continue producing 2 separate nuget packages.

Pros:

• Dependency management is trivial (building/releasing)
• One entry point for all agents in .net

Cons:

• Packages will have the same version

[nvborisenko]

Moved codebase and archived common-net.