refactor: convert solution to .slnx format (#11)

Converts from legacy .sln format to the new XML-based .slnx format.
Updates workflow to reference the new solution file.

Author: CalvinAllen

.github/workflows/release_build_and_deploy.yml

@@ -27,7 +27,7 @@ jobs:
         extension-source-file: 'src/CodingWithCalvin.OpenBinFolder/source.extension.cs'
 
     - name: 2. Restoring Packages
-      run: nuget restore src/CodingWithCalvin.OpenBinFolder.sln
+      run: nuget restore src/CodingWithCalvin.OpenBinFolder.slnx
 
     - name: 3. Building Project
       run: msbuild 'src/CodingWithCalvin.OpenBinFolder/CodingWithCalvin.OpenBinFolder.csproj' /p:configuration='Release' /p:platform='x64' /p:DeployExtension=False

src/CodingWithCalvin.OpenBinFolder.sln

@@ -0,0 +1,14 @@
+<Solution>
+  <Configurations>
+    <Configuration Name="Debug" />
+    <Configuration Name="Release" />
+    <Platform Name="x64" />
+  </Configurations>
+  <Folder Name="/Solution Items/">
+    <File Path="../.github/workflows/publish.yml" />
+    <File Path="../.github/workflows/release_build_and_deploy.yml" />
+    <File Path="../README.md" />
+    <File Path="../resources/extension.manifest.json" />
+  </Folder>
+  <Project Path="CodingWithCalvin.OpenBinFolder/CodingWithCalvin.OpenBinFolder.csproj" />
+</Solution>