Better Nuget V3 API and async caching

[Thorium]

Better Nuget V3 API and async caching.
Public API and Nuget V2 API calls to Async.RunSynchronously should be still refactored away to be real async, but those would cause function signature changes and for that reason bigger refactoring.

[forki]

so what is doing? or what was the problem?

[Thorium]

getNuGetV3Resource function was doing network fetching but:

• getNuGetV3Resource errors were swallowed also in verbose mode. Not after this commit.
• cache was not thread-safe. After this commit it is.
• network operation was sync, not async. Because "Async.RunSynchronously" is actually sync. It's still sync.

[Thorium]

The build is already failing before this...

[forki]

💋