Updates solution to use .slnx format

Migrates the solution file from the old .sln format to the new .slnx
format.

This improves solution loading times and organization within Visual Studio.

Author: niemyjski

.vscode/tasks.json

@@ -11,7 +11,7 @@
       },
       "args": [
         "build",
-        "${workspaceFolder}/Foundatio.Repositories.sln",
+        "${workspaceFolder}/Foundatio.Repositories.slnx",
         "/p:GenerateFullPaths=true"
       ],
       "problemMatcher": "$msCompile"
@@ -47,7 +47,7 @@
       "problemMatcher": "$msCompile"
     },
     {
-      "label": "pack", 
+      "label": "pack",
       "command": "dotnet pack -c Release -o ${workspaceFolder}/artifacts",
       "type": "shell",
       "problemMatcher": []

Foundatio.Repositories.sln

@@ -0,0 +1,22 @@
+<Solution>
+  <Folder Name="/Samples/">
+    <Project Path="samples/Foundatio.SampleApp/Client/Foundatio.SampleApp.Client.csproj" />
+    <Project Path="samples/Foundatio.SampleApp/Server/Foundatio.SampleApp.Server.csproj" />
+    <Project Path="samples/Foundatio.SampleApp/Shared/Foundatio.SampleApp.Shared.csproj" />
+  </Folder>
+  <Folder Name="/Solution Items/">
+    <File Path=".editorconfig" />
+    <File Path=".github/workflows/build.yml" />
+    <File Path="build/common.props" />
+    <File Path="docker-compose.yml" />
+    <File Path="global.json" />
+    <File Path="NuGet.config" />
+    <File Path="README.md" />
+    <File Path="src/Directory.Build.props" />
+    <File Path="tests/Directory.Build.props" />
+  </Folder>
+  <Project Path="src/Foundatio.Repositories.Elasticsearch/Foundatio.Repositories.Elasticsearch.csproj" />
+  <Project Path="src/Foundatio.Repositories/Foundatio.Repositories.csproj" />
+  <Project Path="tests/Foundatio.Repositories.Elasticsearch.Tests/Foundatio.Repositories.Elasticsearch.Tests.csproj" />
+  <Project Path="tests/Foundatio.Repositories.Tests/Foundatio.Repositories.Tests.csproj" />
+</Solution>