enable preview LSP support in VS (#6945)

* enable preview LSP support

Includes plumbing and a stub for `textDocument/hover` (e.g., QuickInfo).

* enable easy exclusion of the language server from VS components

* Update src/fsharp/FSharp.Compiler.LanguageServer/TextDocument.fs

Co-Authored-By: Phillip Carter <pcarter@fastmail.com>

Author: 2 people

eng/Signing.props

@@ -0,0 +1,8 @@
+<Project>
+
+  <ItemGroup>
+    <FileSignInfo Include="Nerdbank.Streams.dll" CertificateName="None" />
+    <FileSignInfo Include="Newtonsoft.Json.dll" CertificateName="None" />
+  </ItemGroup>
+
+</Project>

eng/Versions.props

@@ -107,7 +107,7 @@
     <SystemThreadingTasksParallelVersion>4.3.0</SystemThreadingTasksParallelVersion>
     <SystemThreadingThreadVersion>4.3.0</SystemThreadingThreadVersion>
     <SystemThreadingThreadPoolVersion>4.3.0</SystemThreadingThreadPoolVersion>
-    <SystemValueTupleVersion>4.4.0</SystemValueTupleVersion>
+    <SystemValueTupleVersion>4.5.0</SystemValueTupleVersion>
     <!-- Roslyn packages -->
     <MicrosoftCodeAnalysisEditorFeaturesVersion>$(RoslynVersion)</MicrosoftCodeAnalysisEditorFeaturesVersion>
     <MicrosoftCodeAnalysisEditorFeaturesTextVersion>$(RoslynVersion)</MicrosoftCodeAnalysisEditorFeaturesTextVersion>
@@ -129,6 +129,7 @@
     <MicrosoftVisualStudioEditorVersion>16.0.467</MicrosoftVisualStudioEditorVersion>
     <MicrosoftVisualStudioImageCatalogVersion>16.0.28727</MicrosoftVisualStudioImageCatalogVersion>
     <MicrosoftVisualStudioImagingVersion>16.0.28729</MicrosoftVisualStudioImagingVersion>
+    <MicrosoftVisualStudioLanguageServerClientVersion>16.1.3121</MicrosoftVisualStudioLanguageServerClientVersion>
     <MicrosoftVisualStudioLanguageStandardClassificationVersion>16.0.467</MicrosoftVisualStudioLanguageStandardClassificationVersion>
     <MicrosoftVisualStudioLanguageVersion>16.0.467</MicrosoftVisualStudioLanguageVersion>
     <MicrosoftVisualStudioLanguageIntellisenseVersion>16.0.467</MicrosoftVisualStudioLanguageIntellisenseVersion>

eng/targets/Settings.props

@@ -7,4 +7,8 @@
     <NuspecBasePath>$(ArtifactsBinDir)</NuspecBasePath>
   </PropertyGroup>
 
+  <PropertyGroup>
+    <IncludeVsLanguageServer>true</IncludeVsLanguageServer>
+  </PropertyGroup>
+
 </Project>