NuGet credential plugin V2

[nkolev92]

Spec

Parent feature issue: #6486

• Refactoring of Credential Service/Auth code to prepare for the new plugin architecture.

• Enhance the IPC plugin protocol to add auth operation and auth message capabilities #6699 Enhance the IPC plugin protocol to add auth operation and auth message capabilities.
  Related https://github.com/NuGet/Home/wiki/NuGet-Package-Download-Plugin
  Rev up the plugin protocol, add messages for credential retrieval.
  This should unblock actual credential provider work

• Discovery of plugins - Discovery of plugins #6704

• Protocol cleanup, cross-plat start-up Protocol Cleanup - timeouts, plugin ordering, instantiation xplat #6706

• perf cost of startup Address perf cost of discovering plugins #6744 - As of 4/9/2018

• Logging contract for the auth plugin - Consider adding a logging contract to the plugin protocol #6762

• Credential Provider + Proxy scenario - Consider how to solve the credential plugin + proxy scenario #6923

• Address cross-plat plugin trust validation - Cross-plat plugin trust validation for nuget plugins #6702
  The trust validation is done with Authenticode and it doesn't have a XPLAT story.

• Add caching of capaibilities for plugins - Add caching of capabilities for the plugin #6796

• The authenticode signature validation needs to be lazy - The authenticode signature validation needs to be lazy #6984

• Understand the additional scenarios for the plugin - Understand the additional scenarios with the new plugin #6956

• Add interactive flag for the restoretask and the add pkg ref commands - Add interactive flag for the restoretask and the add pkg ref commands #7017

• Documentation - https://github.com/NuGet/docs.microsoft.com-nuget/issues/909
  Bugs found during development:

• The serialization of GetAuthenticationCredentialRequest is incorrect - The serialization of GetAuthenticationCredentialRequest is incorrect #6983

• Add plugins cache clearing to the locals command - Add plugins cache clearing to the locals command #7075

• The MSBuild SDK resolver should do auth and MSBuild auth should be device flow - The MSBuild SDK resolver should do auth and MSBuild auth should be device flow #7076

Post 4.8

• Cleanup of Default Cred Provider - Rename DefaultCredentialsCredentialProvider to something more meaningful #6780

//cc
@dtivel @rrelyea

[rrelyea]

@nkolev92 - do we close this now? or push to 5.0?

[nkolev92]

I think we can close it.

The few leftover items have their own issues already.