Language Server Protocol was created for VS-Code (not the Visual Studio IDE). It is a rather sensible idea about providing language services like various linting and code-completion (intillisense). It is by no means the first-time that idea has been had, but it has seen rather rapid and wide-scale support from a large number of languages.
Is it used by Visual Studio 2017? I can't seem to find the creating extensions docs for 2017. eg the 2015 docs here.
If not, is there an official language server plugin that allows LSP resources to be used?
Update (Feb 2019): support for the Language Server Protocol is now built in to Visual Studio 2017.
This question was not able to answer, as only Microsoft holds the key. But luckily after half a year, Microsoft did announce the fact that Visual Studio would support LSP,
The extension only works for Visual Studio Preview builds right now, and also lacks many important features,
https://marketplace.visualstudio.com/items?itemName=vsext.LanguageServerClientPreview
We can see that there is still a long way to go.